Public Browser
Public Browser is a token-efficient MCP server for automating Chrome via CDP, with stable accessibility-tree refs, multi-tab support, and an optional self-learning pattern engine.
Browse and observe pages:
navigate,view_page(compact a11y-tree with stable refs),capture_image,tab_status,virtual_desk,dom_snapshot,console_logs,network_monitor,wait_for,observeInteract with pages:
click,type,fill_form,press_key,scroll,drag,file_upload,handle_dialog,download, plus native CDP mouse/keyboard eventsManage tabs: list, switch, open, and close tabs via
virtual_deskandswitch_tabScript and automate workflows:
run_plan(multi-step plans with variables, conditions, suspend/resume, parallel tabs),batch_evaluate(same JS across multiple URLs),set_page_data,evaluate(JS in page context)Configure sessions: set Chrome profiles, session defaults, timeouts, and auto-promote suggestions via
configure_sessionLaunch Chrome with real profiles or headless mode, attach to existing Chrome via WebSocket or use a pipe transport with no listening port
Download files with hash and naming controls, quarantine-friendly directories, and status/list polling
Use from Python via a Script API (HTTP to port 9223) with shared core tools plus direct CDP escape hatch
Run multiple isolated instances via the Node library (
createSession) with per-session caches, process/worker isolation, and environment allowlistingLeverage Cortex: page classification, pattern recording, Markov-based next-tool hints, and optional opt-in telemetry (off by default)
Provides tools for automating Chrome browser via the DevTools Protocol, enabling actions like navigating pages, clicking, typing, form filling, and more.
Click on "Install Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@Public BrowserNavigate to example.com and click the first link."
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
Public Browser
Lets Claude Code and Cursor drive Chrome — with your real, logged-in profile. On the same 30-test benchmark page it used 30% fewer tokens, 25% less money, 41% fewer tool calls and 40% less time than Playwright MCP at the same pass rate — two runs each, 2026-09-03, driver Claude Opus 5, raw data in the repo (Benchmarks, including where it loses). Its own tool definitions are 34% smaller since v2.10.4 (7,607 → 4,990 tokens, reproduce with node scripts/token-count.mjs). Direct CDP, a11y-tree refs, multi-tab ready — 2,360 TypeScript tests, 237 Python tests.
Built for Claude Code, Cursor, and any MCP-compatible client.
Looking for an alternative to Playwright MCP, Browser MCP, or claude-in-chrome? Public Browser talks to Chrome directly via the DevTools Protocol — no Playwright dependency, no Chrome extension bridge, no single-tab limit. One command to install, zero config. See benchmark comparison below.
Why Public Browser?
Every Chrome MCP server has the same problem: bulky responses, too few reliable refs. Screenshots return 10-30x more context payload than text trees. Selector-based refs break the second the DOM rerenders. Extension bridges (Browser MCP) get stuck on the connected tab. Playwright wrappers spin up a new browser instance for every session.
Public Browser fixes this. It talks directly to Chrome via CDP (same protocol Playwright and Puppeteer use internally), returns an accessibility-tree-based reference map, and caches it across calls so click(ref: 'e5') and type(ref: 'e7', ...) survive scrolls and DOM updates.
Benchmark rows below are April 2026, 35-test suite, Opus 4.6 unless a cell also gives a September value. Cells marked Sep come from the blind September 2026 re-run (35-test page, 30 scored, driver claude-opus-5, two runs per required server; one browser-use run) — run files public-browser-run1/2.json, playwright-mcp-run5/6.json, chrome-devtools-mcp-run3/4.json, browser-use-run6.json in test-hardest/results/. Cross-suite comparison is not valid; see Benchmarks.
What you get | Playwright MCP | Browser MCP | claude-in-chrome | browser-use | Public Browser |
Benchmark pass rate (Apr 2026: 31 scored / Sep 2026: 30 scored) | 29/31 (563s)Sep: 30/30 (468s, 493s) | 6/31, abortedSep: not re-run | (24-test suite only) | 21/31 (1870s)Sep: 24/30, incomplete run (2023s) | 30/31 (598s)Sep: 30/30 (281s, 296s) |
Session tokens, whole run (Sep 2026 only) | Sep: 8.8M, 9.6M | — | — | Sep: 56.2M, incomplete run | Sep: 6.3M, 6.5M (−30%) |
Cost per run, Opus 5 list price (Sep 2026 only) | Sep: $4.28, $4.78 | — | — | Sep: $25.25, incomplete run | Sep: $3.41, $3.35 (−25%) |
Avg Tool-Response (Chars) | 1,448Sep: 740, 656 | — | — | — | 807Sep: 1,298, 1,214 |
P95 Tool-Response (Chars) | 8,068Sep: 3,617, 1,587 | — | — | — | 2,328Sep: 6,077, 6,479 |
| 6,084 ( | — | — | — | 1,124Sep: 2,841, 3,398 |
Multi-tab support | Yes | No (single tab) | Yes | Partial | Yes |
Connection | New browser | Extension bridge | Extension | Subprocess | Direct CDP (pipe or WebSocket) |
Ref system | Playwright refs | Playwright refs | CSS selectors | Screenshots | A11y-tree refs (stable across DOM changes) |
Drag & drop | Yes | No | Partial | No | Yes (native CDP mouse events) |
Shadow DOM + iframe | Yes | Yes | Partial | No | Yes (with OOPIF session support) |
Multi-step plan execution | — | — | — | — |
|
P95 is not computed the same way in both rows: the April values are the largest per-tool P95 (by_tool[].p95_chars, jq index floor((n-1)·0.95)), the September values are a nearest-rank P95 over all MCP calls of a run. Do not read the April and Sep P95 numbers as one series.
What changed since April. In April 2026 Public Browser's page views were 5.4x smaller than Playwright MCP's; Playwright MCP 0.0.80 has since made its snapshot format much more compact, so in the September runs its individual responses are smaller than ours (Ø 740 and 656 chars against 1,298 and 1,214) and the tool-response payload summed over a whole run is roughly a tie (109,075 / 104,432 chars against 101,478 / 99,147) — "smallest responses" is no longer a claim we can make. What the model actually consumed over the whole session is a different story: 6.3M and 6.5M tokens against 8.8M and 9.6M (~30% fewer), $3.41 and $3.35 against $4.28 and $4.78 at Opus 5 list price (~25% less). That gap comes from the second thing left standing: ~41% fewer tool calls (84 and 86 against 137 and 151) and ~40% less time to finish (281s and 296s against 468s and 493s, page timer; 34% on the full wall clock, 331s and 346s against 501s and 527s) at the same reliability, 30/30 in each of those four runs. Every call re-reads the whole conversation so far, so fewer calls means fewer re-reads — that is where the token and cost gap comes from, not from smaller responses. The advantage moved from "cheaper per look" to "cheaper per task", and the headline was changed accordingly.
September 2026 data, both runs per server, against Playwright MCP 0.0.80. Rows where the bar runs past the line are rows Public Browser loses. Method and the full table: Benchmarks.
Related MCP server: chrome-devtools-slim
Quick Start
Install in Claude Code
One command — installs globally for all projects:
claude mcp add --scope user public-browser npx -y public-browser@latestImportant: after claude mcp add you must fully quit and reopen Claude Code. /mcp reconnect is not enough — Claude Code reads the mcpServers config only at session start and caches it. After the restart, the first tool call auto-launches Chrome visible (no headless, no port setup). Done.
To enable parallel Python Script API access, add
--scriptto the args:claude mcp add --scope user public-browser npx -y public-browser@latest -- --script
Install in Cursor
Add to ~/.cursor/mcp.json:
{
"mcpServers": {
"public-browser": {
"command": "npx",
"args": ["-y", "public-browser@latest"]
}
}
}For parallel Python Script API access, use
"args": ["-y", "public-browser@latest", "--", "--script"]
Install in Cline
Add to your cline_mcp_settings.json:
{
"mcpServers": {
"public-browser": {
"command": "npx",
"args": ["-y", "public-browser@latest"]
}
}
}Install in other MCP clients
Any client that supports stdio MCP servers: npx -y public-browser@latest with no arguments.
Try it — your first prompt
After installing, paste this into your AI coding assistant:
Open mcp-test.second-truth.com, read the page, and fill the contact form with Name "Test User" and Email "test@example.com".
This exercises three core tools in sequence: navigate loads the page, view_page reads the accessibility tree with stable element refs, and fill_form fills multiple fields in one call. You should see Chrome open, the page load, and the form filled — all without writing a single line of code.
Uninstall
claude mcp remove --scope user public-browserChrome Profiles
By default, Public Browser starts Chrome with a fresh temp profile — no cookies, no logins, no extensions. For tasks like research on sites that block anonymous visitors, you can launch Chrome with your real profile instead.
List available profiles
npx public-browser profilesLaunch with a profile
Three ways — pick whichever fits your setup:
# CLI flag
npx public-browser --profile "Julian"
# Environment variable
PUBLIC_BROWSER_PROFILE="Julian" npx public-browser
# MCP tool (call BEFORE any browser interaction)
configure_session({ profile: "Julian" })When using a real profile, Public Browser preserves extensions, cookies, logins, and sync. It creates a lightweight wrapper directory with a symlink to your real profile data — Chrome gets a "non-default" data dir (required for remote debugging) while using your actual profile.
If Chrome is already open
Public Browser detects this via lock-file inspection. If Chrome is running with remote debugging enabled, it attaches via CDP. If not, it shows a clear error asking you to close Chrome first.
Script API (Python)
A second way to use Public Browser — deterministic browser automation from Python, without an LLM in the loop. Scripts use the same tool implementations as the MCP server (Shared Core) — every improvement to click, navigate, fill_form etc. automatically benefits your scripts too. The MCP server handles AI-driven workflows; the Script API is for repeatable scripts you write yourself.
How fast that is without an LLM: a scripted run of the 24-test version of the benchmark suite finished the whole suite in 21 seconds (type: mcp-scripted, 2026-04-04). That number says what deterministic scripting costs, not how Public Browser compares to other MCP servers — every cross-server comparison in Benchmarks is LLM-driven on both sides.
Installation
pip install publicbrowserOr, from a source checkout, install the local package:
python -m pip install ./pythonChrome.connect() auto-starts the Public Browser server as a subprocess via a local public-browser binary or the npx fallback — no manual Chrome launch or port setup needed.
Legacy single-file alternative: For quick prototyping you can copy
python/publicbrowser_standalone.pyinto your project. This uses v1 direct CDP and does not benefit from server-side improvements — use the localpublicbrowserpackage for the full Shared Core experience.
How it works
Python Script Escape Hatch (Power User)
| |
v v
HTTP POST /tool/{name} WebSocket (CDP)
Port 9223 Port 9222
| |
v |
Public Browser Server |
| |
v |
registry.executeTool() |
| |
v |
Tool Handler |
(click.ts, navigate.ts, ...) |
| |
v v
Chrome <------------ CDP --------------->Your script sends HTTP requests to the Public Browser server on port 9223. The server executes the exact same tool handlers that the MCP server uses — one codebase, one test suite (2300+ tests), two access paths.
Auto-Start
Chrome.connect() finds and starts the server automatically:
Running server — checks if port 9223 already responds, connects immediately
PATH binary — finds
public-browserin PATH, starts it with--scriptnpx fallback — runs
npx -y public-browser@latest -- --scriptExplicit path —
Chrome.connect(server_path="/path/to/public-browser")for custom setups
Example: Login + Data Extraction
from publicbrowser import Chrome
chrome = Chrome.connect()
with chrome.new_page() as page:
page.navigate("https://competitor.example.com/login")
page.fill({"#email": "tomek@shop.de", "#password": "***"})
page.click("button[type=submit]")
page.wait_for("text=Dashboard")
for cat in ["electronics", "furniture", "toys"]:
page.navigate(f"https://competitor.example.com/prices/{cat}")
prices = page.evaluate(
"[...document.querySelectorAll('tr')].map(r => r.textContent)"
)
save_csv(cat, prices)
chrome.close()Methods
Method | Description |
| Connect to or auto-start the Public Browser server |
| Context manager — opens a new tab, auto-closes on exit |
| Navigate and wait for load |
| Click element by CSS selector, text, or ref |
| Type text into an input |
| Fill multiple form fields at once |
| Wait for JS condition or |
| Run JavaScript, return result |
| Enable downloads, return download dir |
| Close the tab (auto-called by context manager) |
| Escape Hatch — direct CDP access via WebSocket (see below) |
Escape Hatch: Direct CDP Access
For use cases the high-level API doesn't cover — network interception, console log subscriptions, performance tracing, cookie management — you can drop down to raw CDP commands:
with chrome.new_page() as page:
page.navigate("https://example.com")
# Enable network tracking
page.cdp.send("Network.enable")
# Get all cookies
cookies = page.cdp.send("Network.getAllCookies")
# Performance tracing
page.cdp.send("Tracing.start", {"categories": "-*,devtools.timeline"})The Escape Hatch communicates directly with Chrome via WebSocket (port 9222), bypassing the server. It connects lazily on the first send() call and reuses the connection for subsequent calls. Each page gets its own WebSocket routed to the correct tab.
MCP Coexistence
When the MCP server and Python scripts need to run at the same time, add --script to the MCP config. Chrome.connect() handles the rest automatically — each script works in its own tab, MCP tabs are never touched.
Enabling --script in MCP Config
Claude Code:
claude mcp add --scope user public-browser npx -y public-browser@latest -- --scriptCursor / Cline (mcp.json):
{
"mcpServers": {
"public-browser": {
"command": "npx",
"args": ["-y", "public-browser@latest", "--", "--script"]
}
}
}See python/README.md for the full API reference and advanced examples.
Node Library API (multiple instances in one process)
The MCP server and the Python Script API both drive exactly one Chrome per
process. When you need several browsers at once — say a read-only research
browser and a separate action browser per agent — spawning one
npx public-browser per instance costs 4–6 s of start-up each. createSession()
runs the same session inside your own Node process instead:
import { createSession } from "public-browser";
const research = await createSession({
cdpUrl: "http://127.0.0.1:9333", // or cdpPort: 9333
userDataDir: "/var/agents/a1/research", // created if missing
headless: true,
stealth: false, // stay identifiable — see below
downloadDir: "/var/agents/a1/quarantine", // never deleted by us
downloadHash: true, // adds sha256 to every download
downloadNaming: "suggested", // real filenames, not GUIDs
cortexDir: "/var/agents/a1/cortex", // per-instance pattern store
inheritEnv: ["HTTPS_PROXY"], // opt in — see Environment below
});
const action = await createSession({ cdpPort: 9334, userDataDir: "/var/agents/a1/action" });
await research.callTool("navigate", { url: "https://example.com" });
const page = await research.callTool("view_page", {});
await research.close();
await action.close();callTool(name, params) takes the same tool names and parameters as the MCP
tools (navigate, view_page, click, type, fill_form, run_plan,
download, ...) and routes through the identical handlers (Shared Core).
Isolation. Each session runs in its own worker thread by default, so the module-level caches (element refs, selector cache, viewport state, stealth flag, cortex matcher) exist once per session rather than once per process — two sessions can never hand each other stale element refs.
Measured on macOS with isolation: "process", attaching to a Chrome started
outside Public Browser (a worker thread saves ~40 ms):
Median | |
| ~0.9 s |
| ~0.7 s |
...through to a real page navigated and read | ~1.8 s |
Most of the attach cost is Chrome starting a renderer for the tab Public Browser opens for itself — an attached session never takes over tabs that belong to someone else.
A thread is not a security boundary: same process memory, same file
descriptors. isolation: "process" forks one OS process per session instead —
separate heap, separate descriptors, separate crash domain — for integrators
whose trust model draws the line there. isolation: "inline" skips isolation
altogether and is only correct when the thread runs exactly one session.
| Boundary | Startup | Use when |
| thread — private module caches | ~1 s | several sessions in one trusted process |
| OS process — private memory + descriptors | ~1 s | the sessions must not share a process with the host |
| none — the calling thread | fastest | exactly one session per thread |
No listening CDP port (transport: "pipe"). By default Chrome is launched
with --remote-debugging-port, which is what makes --attach, the Script API
and reconnect-after-crash possible — and which also means every other process
on the machine can drive that browser. For a session holding real logins that
is a way around any permission check you perform yourself.
const action = await createSession({
transport: "pipe", // no --remote-debugging-port at all
userDataDir: "/var/agents/a1/action",
headless: true,
});CDP then travels over the child's stdio pipe, which only Public Browser holds:
lsof shows nothing listening and a second process finds no way in. The price
is everything the port paid for — no reconnect after a Chrome crash, no second
client, no attach, and no named profile (Chrome rejects the pipe with a
real user profile). Both contradictions fail at createSession() rather than
at the first tool call. session.transport reports which mode is in use, and
session.cdpPort is undefined — there is no port, and reporting the default
would name whatever Chrome the user has open on 9222.
Environment. A session does not start from the host environment. It starts from a documented minimum and you widen it deliberately — an orchestrator holding cloud credentials, API keys and tokens should not hand them to a browser session just because the two share a process tree.
What a session always gets is ESSENTIAL_ENV_VARS: PATH, HOME, the temp
dir, CHROME_PATH, locale/timezone, the Linux display variables and the
Windows process basics. Everything else is opt-in:
// PATH/HOME/CHROME_PATH plus the proxy — and nothing else from the host.
await createSession({ inheritEnv: ["HTTPS_PROXY", "NO_PROXY"] });
// Full inheritance, the pre-2.8 behaviour.
await createSession({ inheritEnv: true });Proxy variables are deliberately not essential: a proxy URL can carry credentials, so it is allowlisted on purpose rather than inherited by accident.
On top of that, a session never inherits Public Browser's own SILBERCUE_* /
PUBLIC_BROWSER_* configuration variables — in any inheritEnv mode. Each of
them has an option here, and a host-level variable, usually set for the host's
own Chrome, silently redirecting a configured session is a bug, not a feature:
with SILBERCUE_CHROME_HOST=10.9.9.9 in the orchestrator's environment, a
session created with cdpPort: 9450 still talks to 127.0.0.1:9450. Use env
to set one back deliberately.
Shutdown. close() resolves only once Chrome is actually gone — SIGTERM,
SIGKILL after 5 s — so the port and the user-data-dir are free for the next
launch instead of racing a process that was merely asked to exit.
One session per Chrome. Some CDP settings are browser-wide rather than
per-session, Browser.setDownloadBehavior among them: two sessions attached to
the same Chrome share one download directory, and whichever connected last
wins.
This fails silently and it corrupts the record: the losing session keeps
reporting paths under its downloadDir, but the file was written to the
other one. path then points at nothing, with no error to notice. Give each
session its own Chrome — its own port (or transport: "pipe") and its own
user-data-dir — whenever downloadDir matters.
Option | Default | Description |
| — |
|
|
| CDP endpoint this session drives. |
| — | Chrome |
| — | Named Chrome profile instead of a raw directory |
|
| Launch Chrome headless |
|
|
|
|
| Never auto-launch; attach to a running Chrome and fail fast if there is none |
| temp dir | Where downloads land. A directory you supply is never deleted |
|
| Report |
|
|
|
|
| Per-instance cortex store |
|
|
|
|
| Essentials only. Array = essentials + allowlist, |
| — | Extra environment variables for the session, applied last |
|
|
|
|
| Launch/attach during |
|
| Budget for the session thread/process to report ready |
Multiple instances via the CLI
The same thing without a Node host — one process per Chrome, each on its own port:
public-browser --port 9333 --profile research --download-dir /q/research
public-browser --port 9334 --profile action --download-dir /q/action--profile <name> uses one of your real Chrome profiles. For a throwaway
per-agent Chrome, point at a raw directory instead — it is created if missing:
public-browser --port 9335 --user-data-dir /var/agents/a3/chrome--attach connects to an already-running Chrome on the configured port instead
of launching one. SILBERCUE_CHROME_PORT and SILBERCUE_SCRIPT_PORT are the
environment equivalents of --port and --script-port and are part of the
stable public contract.
Identifiable automation (--no-stealth)
By default Public Browser masks navigator.webdriver (it reports undefined)
and launches Chrome with --disable-blink-features=AutomationControlled. That
is the right default for consumer automation, but the wrong one when your
integration must be transparently identifiable as a bot — compliance-driven
crawling, internal agent fleets, or sites whose terms require honest signalling.
Turn the masking off completely:
public-browser --no-stealth
# or
SILBERCUE_STEALTH=0 npx public-browserawait createSession({ stealth: false });With stealth off, navigator.webdriver stays true and keeps its native
getter (Object.getOwnPropertyDescriptor(Navigator.prototype, "webdriver").get
still reports [native code]) — permanently, across navigations and tab
switches, with no post-correction needed on your side. No masking script is
injected at any point and the launch flag is omitted.
Downloads
Downloads land in a per-session temp directory that is removed on shutdown.
Point them at a directory of your own — a quarantine dir, a shared volume — with
--download-dir / PUBLIC_BROWSER_DOWNLOAD_DIR / downloadDir. A directory you
supply is created if missing and never deleted by Public Browser.
With --download-hash (or downloadHash: true) every completed download also
carries a sha256, so the download tool returns path, size and digest:
{"filename":"report.pdf","path":"/q/research/A1B2...","size":48213,"sizeKb":48,
"url":"https://example.com/report.pdf","sha256":"9f86d081884c7d659a2f..."}Filenames. Chrome writes downloads under their internal GUID, so the file on
disk is called A1B2... and only the filename field carries the real name.
That is fine when you read the JSON, and useless when something else has to walk
the directory. --download-naming suggested (or downloadNaming: "suggested",
PUBLIC_BROWSER_DOWNLOAD_NAMING=suggested) renames each finished file to the
server-supplied name:
{"filename":"report.pdf","path":"/q/research/report.pdf","size":48213,"sizeKb":48,
"url":"https://example.com/report.pdf","sha256":"9f86d081884c7d659a2f..."}The name is sanitised before it touches the disk — basename only, no control
characters, never hidden, length-capped — and a collision gets a -1, -2, ...
suffix rather than overwriting an existing file. filename always reports the
name the file actually has, so join(downloadDir, filename) equals path. If
the rename fails, the GUID path and the raw server name are kept and reported;
a download is never lost to a naming problem.
Timing. action: "status" waits up to 250 ms for a download to start
before reporting that there is none, because Chrome fires downloadWillBegin a
few milliseconds after the click that triggers it — without the window, the
first call after a click misses a file that is already on its way. Adjust it per
call with settle ({"action":"status","settle":0} for an instant check,
5000 for a slow server). Once a download has started, status waits for it to
finish, bounded by timeout.
For polling loops use action: "list" — it returns the full session history
immediately and never waits, for either a start or a completion.
Tool Overview
Tool | Description |
Reading & Observation | |
| A11y-tree with stable |
| WebP screenshot, max 800px, <100KB. For visual verification only — refs come from |
| Browser console output with level/pattern filters |
| Start/stop/query network requests with filtering |
| Watch DOM changes: |
| Wait for element visible, page text, URL, network idle, or JS expression. |
| Active tab's cached URL/title/ready/errors (0ms) |
| Lists all tabs with stable IDs. Call first in every session. |
| Bounding boxes, computed styles, paint order. For spatial questions |
Interaction | |
| Real CDP mouse events by ref, selector, text, or coordinates. The DOM diff (NEW/REMOVED/CHANGED) arrives with the next response, or in this one with |
| Type into an input by ref/selector |
| Fill a complete form in one call — text, |
| Real CDP keyboard events — Enter, Escape, Tab, arrows, shortcuts (Ctrl+K, etc.) |
| Scroll page, element into view, or inside a specific container |
| Upload file(s) to |
| Configure |
| Native CDP drag & drop between elements |
| Wait for pending downloads or list downloaded session files |
Navigation | |
| Load a URL. First call per session auto-redirected to |
| Open, switch to, or close tabs by ID from |
Scripting | |
| Multi-step batch execution with variables, conditions, |
| View/set session defaults (tab, timeout) and accept auto-promote suggestions |
| Visit multiple URLs sequentially and run the same JavaScript expression on each page. |
| Write large payloads to |
| Execute JS in page context. Anti-pattern scanner warns on |
Why an MCP server and not a CLI?
Several browser-automation projects now ship a CLI and tell coding agents to call it from the shell; Microsoft's Playwright README recommends that route. A CLI adds no tool definitions to the context. The trade-off is that the model has to learn the command surface from --help output and error messages. In one practitioner's side-by-side of Chrome DevTools MCP and the agent-browser CLI, the MCP tool surface came out better and the models "do not seem deeply fluent with it yet" (Pasi Huuhka, 28 Jan 2026) — one comparison, not a study.
Public Browser keeps the MCP surface and keeps it under a fixed budget: its 25 tool definitions take about 4,990 tokens of context as delivered over the wire (characters / 4 of the tools/list response, npm run token-count; measured the same way with node scripts/token-count.mjs --cmd npx --args "-y @playwright/mcp@0.0.80", Playwright MCP 0.0.80 takes 4,626 and Chrome DevTools MCP 1.8.0 takes 6,290). Chars / 4 is a coarse proxy — your client's /context figure will differ, but it is the same proxy for all three servers. A test enforces the budget, so it cannot creep back up. Getting there cost nothing in the benchmark: the two acceptance runs of the shortened definitions solved 30/30 with 80 and 68 calls, against 84 and 86 for the previous wording (raw data in test-hardest/results-local/).
The other argument for a CLI — "MCP needs a round-trip per step" — is what run_plan is for: N steps in one call, executed server-side with variables, conditions and suspend/resume. In the same two acceptance runs that was 49% fewer tool calls than Playwright MCP (80 and 68 against 137 and 151, same pass rate); the headline's 41% comes from the published September runs with the previous wording (84 and 86 calls, see Benchmarks).
Coming from Browser MCP?
Browser MCP (@browsermcp/mcp) has had no release since 0.1.3 on 11 April 2025, and its extension bridge works on one tab. If you picked it for its four promises, here is what Public Browser does for each: Fast — talks to Chrome directly over CDP, no extension bridge, no cloud hop; Private — runs on your machine, telemetry is opt-in; Logged In — can drive your real, logged-in Chrome profile (see Chrome Profiles); Stealth — sends real CDP input events (not synthetic JS events) and masks navigator.webdriver; --no-stealth makes the automation identifiable when you want that. Install with one command (Quick Start). Tool names differ: browser_snapshot → view_page, browser_click → click, browser_type → type; view_page returns the refs that click and type take. Multi-tab works.
Benchmarks
Two data sets, measured on https://mcp-test.second-truth.com: a September 2026 blind re-run (current) and the April 2026 runs kept for history. Cross-suite and cross-model comparisons are not valid — compare rows only inside one data set. Raw run JSONs, the full method and the environment matrix are in test-hardest/README.md.
September 2026 (current)
2026-09-03, 35-test page with 30 scored (T5.3–T5.6 can only be started by the page's own runner; T4.7 grades a self-reported token count and was dropped for everyone). One fresh blind Claude Code session per run in print mode, driver model claude-opus-5, exactly one MCP server per session, built-in tools cut down to Write, identical prompt for every server. Two runs each for Public Browser 2.10.1, Playwright MCP 0.0.80 and Chrome DevTools MCP 1.8.0; one run for browser-use 0.12.5. All seven runs are pinned to the same page version (suite.html_sha256 = 81e4b7aa…bed2). Metrics are counted post-hoc from the session transcript via test-hardest/measure-tool-calls.sh — nothing is self-reported by the servers. Table below is the output of node test-hardest/blind-run.mjs compare; method, profiles and losses are documented in test-hardest/README.md.
MCP | Version | Model | Date | Run | Status | Passed | Duration | MCP calls | Response total | Ø response | P95 | Snapshot tool Ø |
browser-use | 0.12.5 | claude-opus-5 | 2026-09-03 | browser-use-run6 | ok | 24/30 | 2023s | 276 | 15800k | 57244 | 321033 | 102819 (18×) |
Chrome DevTools MCP | 1.8.0 | claude-opus-5 | 2026-09-03 | chrome-devtools-mcp-run3 | ok | 29/30 | 547s | 156 | 149k | 954 | 5676 | 4718 (12×) |
Chrome DevTools MCP | 1.8.0 | claude-opus-5 | 2026-09-03 | chrome-devtools-mcp-run4 | ok | 29/30 | 558s | 172 | 120k | 696 | 5271 | 3593 (14×) |
Playwright MCP | 0.0.80 | claude-opus-5 | 2026-09-03 | playwright-mcp-run5 | ok | 30/30 | 468s | 137 | 101k | 740 | 3617 | 1911 (17×) |
Playwright MCP | 0.0.80 | claude-opus-5 | 2026-09-03 | playwright-mcp-run6 | ok | 30/30 | 493s | 151 | 99k | 656 | 1587 | 2269 (14×) |
Public Browser | 2.10.1 | claude-opus-5 | 2026-09-03 | public-browser-run1 | ok | 30/30 | 281s | 84 | 109k | 1298 | 6077 | 2841 (16×) |
Public Browser | 2.10.1 | claude-opus-5 | 2026-09-03 | public-browser-run2 | ok | 30/30 | 296s | 86 | 104k | 1214 | 6479 | 3398 (16×) |
What these two runs show: Public Browser needed 84 and 86 tool calls where Playwright MCP needed 137 and 151 and Chrome DevTools MCP needed 156 and 172, and it finished the page in 281s and 296s against 468s/493s and 547s/558s. Duration here is summary.duration_s, the page's own timer from the first test to the export click — server start, Chrome start and the first navigation are not in it; the full wall clock per run (harness.wall_clock_s) is 331s/346s against 501s/527s and 583s/597s. Pass rate is a tie with Playwright MCP (30/30 in both runs each) and one test ahead of Chrome DevTools MCP: its only miss is T5.2, a CDP-fingerprint check (navigator.webdriver is true under chrome-devtools-mcp) rather than a browser capability; on the other 29 tests it is a tie. browser-use-run6 has complete: false — two tests were never started, so its 24/30 is an incomplete run, not a clean loss.
Where Public Browser loses in these runs: Playwright MCP 0.0.80 returns the smaller responses (Ø 740 and 656 chars against 1,298 and 1,214; browser_snapshot Ø 1911 and 2269 against view_page at 2841 and 3398, whose P95 reaches 9,734), total response volume is a near tie slightly in Playwright's favour (101k/99k against 109k/104k), and per-call click latency is mixed rather than a win — by_tool.avg_ms for click is 90 ms in run 1 but 435 ms in run 2, against 251 and 260 ms for Chrome DevTools MCP. P95 response size over all calls goes against Public Browser in both runs and against both competitors (6077 and 6479 chars against Playwright's 3617 and 1587 and DevTools' 5676 and 5271), and so does the evaluate response (Ø 1913 and 966 chars against browser_evaluate at 1223 and 755 and evaluate_script at 1069 and 488). The April claim that view_page is 5.4x more compact than browser_snapshot does not hold against Playwright MCP 0.0.80.
What changed since April, and where the remaining lead comes from. The April 2026 numbers (35-test suite, Opus 4.6) had Public Browser's page views 5.4x smaller than Playwright MCP's. Playwright MCP 0.0.80 has since made its snapshot format considerably more compact, and in these September runs its single responses are the smaller ones (Ø 740 and 656 chars against 1,298 and 1,214). Summed over a whole run the context payload is about the same on both sides — 109,075 and 104,432 chars for Public Browser against 101,478 and 99,147 for Playwright MCP — so "smallest responses" is not an argument we still have, and we say so. What the model consumed over the whole session is a different measure, and there Public Browser is ahead: tokens.delta (input + output + cache writes + cache reads from the Claude Code transcript) is 6,288,593 and 6,518,119 against 8,783,693 and 9,592,264 — ~30% fewer — and cost_usd_list is $3.41 and $3.35 against $4.28 and $4.78 — ~25% less. Almost all of that volume is cache reads of the growing conversation (4.4M and 4.3M against 6.0M and 6.9M); fresh input is 170–304 tokens per run on every side, so the shared overhead that made session totals useless for comparison in April is not present in these blind runs. Cache reads are billed cheaper than fresh input, which is why the cost gap (25%) is smaller than the token gap (30%) — quote the cost figure when in doubt. What drives both is ~41% fewer tool calls (84 and 86 against 137 and 151) and ~40% less time to finish (281s and 296s against 468s and 493s on the page's own timer), at identical reliability: 30/30 in all four runs. That gap does not come from smaller snapshots — both servers took page snapshots about equally often (view_page 16 and 16 against browser_snapshot 17 and 14). The design hypothesis is that it comes from run_plan, which bundles several steps into one call and was used 22 and 29 times, and from the 1,601 characters (2,358 since v2.10.4, without the Cortex line) of handshake instructions Public Browser sends to tell the model how to work (it is the only server in this field that sends any). Neither was isolated in this benchmark, so treat both as plausible contributors, not as a proven cause. The advantage moved from "cheaper per look" to "cheaper per task", and the headline was changed accordingly. The chart at the top of this file plots these six ratios, wins and losses on one scale; it is regenerated from the run JSON by scripts/make-benchmark-chart-2026-09.py.
April 2026 (historical)
Measured on the same page against the 35-test version of the suite (April 2026) — 5 levels (Basics, Intermediate, Advanced, Hardest, Community Pain Points). Four of the 35 tests are runner-only and are excluded from every score, so all pass rates in this section are out of 31 scorable tests. An extended 42-test version exists locally and is not yet published; the numbers here are not measured against it. Driver model was Claude Opus 4.6 and competitor versions were not recorded. Each run is independent, values on the benchmark page are randomized per page-load, all runs started in a fresh Claude Code session out of /tmp (no project context bias), and all metrics measured post-hoc from the session JSONL via test-hardest/measure-tool-calls.sh — no self-reporting, no MCP-side instrumentation, just counting tool_use blocks and tool_result char lengths.
April 2026 data, 24- and 35-test suites, superseded by the September 2026 rerun above.
Head-to-Head (24-test suite, April 2026 — historical suite version)
All rows LLM-driven by Claude Opus 4.6 on the same test page, one recorded run each. Public Browser ran 2026-04-05, the other servers 2026-04-02. This is the older 24-test version of the suite — do not compare these rows against the 31-scorable-test numbers below.
MCP Server | Tests Passed | Duration | Tool Calls | Speed vs PB |
Public Browser | 24/24 | 350s | 71 | -- |
Playwright MCP | 24/24 | 570s | 138 | 1.6x slower |
browser-use skill | 24/24 | 725s | 117 | 2.1x slower |
claude-in-chrome | 24/24 | 772s | 193 | 2.2x slower |
browser-use | 16/24 | 1813s | 124 | 5.2x slower |
In this one April 2026 run each (24-test suite, Opus 4.6), Public Browser needed 71 tool calls where Playwright
MCP needed 138 — roughly half the roundtrips for the same 24 passes. The September 2026 re-run above is the
current figure: 84 and 86 calls against 137 and 151. Raw data: test-hardest/benchmark-*.json (Public Browser row:
benchmark-silbercuechrome_mcp-llm-2026-04-05.json, type: llm-driven).
Pass Rate + Duration (31 scorable tests, LLM-driven)
Every row is one recorded run; the run id is named so each number is traceable to a single run JSON in
test-hardest/results/. No averaging across runs.
MCP | Passed | Duration | Run |
Public Browser | 30/31 (97%) | 598s | Run 5 |
Playwright MCP | 29/31 (94%) | 563s | Run 2 |
Playwright CLI | 28/31 (90%) | 376s | Run 1 |
Chrome DevTools MCP (Google) | 27/31 (87%) | 535s | Run 2 |
browser-use | 21/31 (68%) | 1870s | Run 5 |
Browser MCP (browsermcp) | 6/31 (19%) | 294s, aborted | Run 1 |
claude-in-chrome | 24-test data only, not re-benched | — | — |
Servers with several recorded runs, so you can see the spread rather than only the row above: Playwright MCP ranges 29–30/31 across three runs (Runs 2–4), its best being 30/31 in 449s (Run 3); Chrome DevTools MCP ranges 27–29/31, its best 29/31 in 518s (Run 1). Run 2 is quoted for both because that is the run the tool-efficiency analysis below instruments end to end. On pass rate this field is effectively a tie — the durable difference is response size, and that holds across every Playwright run measured (avg 1,216–1,467 chars in Runs 2–4).
Tool-Efficiency (the fair metric)
We measure each tool call's response char length directly, group by tool name, estimate tokens via chars/4. Why this metric: in these April runs, session-level token deltas were dominated by LLM overhead (system prompt + CLAUDE.md + conversation history = ~80-90% of the budget) and only showed 5-15% differences between MCPs — untrustworthy for comparing browser servers. Tool-response size is the part the MCP server actually controls. (The September 2026 runs are different: they are blind sessions out of /tmp with no CLAUDE.md and 170–304 fresh input tokens per run, so their session totals are comparable and are quoted above.)
Public Browser Run 5 vs Playwright MCP Run 2 — the same two runs as the pass-rate table above.
Metric | Public Browser | Playwright MCP | Difference |
Tool calls (MCP-only) | 151 | 121 | +25% (PB uses more, smaller calls) |
Avg Response size | 807 Chars | 1,448 Chars | PB 1.8x smaller |
Avg Response tokens est. | 201 | 362 | PB 1.8x smaller |
P95 Response | 2,328 Chars | 8,068 Chars | PB 3.5x smaller |
Total response content | 128k Chars | 175k Chars | PB 27% less |
Per-Tool Breakdown (where the difference comes from)
Tool | Public Browser Avg | Playwright MCP Avg | Verdict |
| 1,124 Chars (21 calls) | 6,084 Chars (8 calls) | PB 5.4x more compact per call |
| 510 Chars (33 calls) | 2,155 Chars (47 calls) | PB 4.2x more compact per call |
| 88 Chars (13 calls) | 147 Chars (13 calls) | PB 1.7x more compact |
| 1,278 Chars (63 calls) | 463 Chars (44 calls) | Playwright 2.8x leaner — but see trade-off below |
¹ recorded as read_page in the April 2026 runs; the tool was renamed to view_page afterwards.
The Ambient-Context trade-off
Ambient Context — Claude sees DOM changes for free, no extra
view_pageneeded
Public Browser's click is 2.8x larger than Playwright's because every click response embeds the DOM diff (NEW/REMOVED/CHANGED lines). Playwright returns a bare confirmation, so the LLM typically follows up with a browser_snapshot or browser_evaluate to see what happened. Over a full benchmark run, Playwright MCP spends 47 browser_evaluate calls averaging 2,155 chars against Public Browser's 33 at 510 chars. Public Browser delivers the diff inline. Net result: PB's click+read_page+evaluate total is 120k chars vs Playwright MCP's 170k — 30% less response content overall.
April 2026, Opus 4.6:
view_pagewas 5.4x more compact than Playwright MCP'sbrowser_snapshot(superseded — against Playwright MCP 0.0.80 in September 2026 it is not)
Measured on the 35-test benchmark (2026-04-09): Public Browser's view_page averages 1,124 chars per call vs Playwright MCP's browser_snapshot at 6,084 chars. Same page, same test suite, same LLM driver. The a11y-tree compression + Ambient Context pipeline meant we only sent what the agent actually needed — smaller responses, less context pressure, cheaper runs. That was the April 2026 picture. Against Playwright MCP 0.0.80 it no longer holds — that release made the snapshot format much more compact, and in the September runs browser_snapshot averages 1,911 and 2,269 chars against view_page at 2,841 and 3,398; see September 2026 (current) above.
See test-hardest/README.md for the full protocol, per-test breakdown, and raw JSON runs with tool_efficiency blocks.
Cortex — Self-Learning Pattern Engine
Public Browser includes a lightweight learning layer called Cortex. It observes which tool sequences work on different page types and feeds that knowledge back as hints to the LLM agent. No ML model, no training step — just deterministic pattern recording and Markov-chain predictions.
How it works
Page Classification — Every page is classified by its accessibility tree into one of 16 functional types:
login,signup,mfa,search_form,search_results,data_table,form_simple,form_wizard,article,navigation,dashboard,settings,media,checkout,profile,error. The classifier is rule-based (ARIA roles, landmarks, keyword signals) — no domains or URLs are involved.Pattern Recording — Successful tool-call sequences (e.g.
navigate → view_page → fill_form → clickon aloginpage) are recorded into a local append-only Merkle log (~/.public-browser/patterns.jsonl). Only page type, tool names, a content hash, and a timestamp are stored — no URLs, no page content, no PII.Markov Predictions — Recorded patterns are ingested into a first-order Markov table that models
P(next_tool | last_tool, page_type). When the agent lands on a page, the Cortex returns the most likely next tools with probabilities. Stale entries decay automatically (0.95/week, removed after 30 days).Community Markov Table — A hand-curated transition table (
community-markov.json) ships with every installation. It contains baseline probabilities for common page types so that new installations benefit from community knowledge immediately, without needing local history. The table is SHA-256 verified at load time and merged with local patterns (local data takes precedence).
Privacy by design
The Cortex stores and transmits only structural metadata — page types (not domains), tool names (not arguments), and content hashes (not content). A login pattern reveals nothing about which login page was visited. The telemetry payload is built via explicit field allowlist (no spread operator), preventing accidental leakage of future fields.
Opt-in telemetry
Telemetry is disabled by default. To contribute your anonymised patterns back to the community table, set PUBLIC_BROWSER_TELEMETRY=1. Uploads go via HTTPS only; non-HTTPS endpoints are rejected. Each pattern is rate-limited to prevent duplicate uploads.
Local friction log (developer opt-in)
For development of Public Browser itself there is a second, fully local opt-in: SILBERCUE_CHROME_FRICTION_LOG=1 makes the server count tool calls, tool errors and detected fallback spirals per run in ~/.silbercue-chrome/friction-queue.json. It records counters, timestamps and the working directory — never page content, URLs or user input — and nothing ever leaves the machine. Without the variable the code path is not entered at all: no file, no counters, no hints.
Architecture
Public Browser (Node.js MCP server, public-browser)
+-- @modelcontextprotocol/sdk (stdio transport)
+-- CDP Client
| +-- WebSocket transport (existing Chrome on :9222)
| +-- Pipe transport (auto-launched Chrome with --remote-debugging-pipe)
+-- Auto-Launch: Chrome + optimal flags, visible by default
+-- A11y-tree cache + Selector cache
+-- Session Manager (OOPIF support for iframes and Shadow DOM)
+-- Tab State Cache (URL/title/ready across tabs)
+-- Cortex (self-learning pattern engine)
| +-- Page Classifier (16 page types from a11y-tree)
| +-- Pattern Recorder + Merkle Log (local persistence)
| +-- Markov Table (transition predictions)
| +-- Community Table (shipped baseline, SHA-256 verified)
| +-- Hint Matcher (delivers predictions to tool responses)
| +-- Telemetry Upload (opt-in, HTTPS, rate-limited)
+-- Script API (Python, source install from ./python)
| +-- Shared Core via HTTP (:9223) — same tool handlers as MCP
| +-- Escape Hatch via WebSocket (:9222) — direct CDP for power users
+-- 25 tools
Reading - Interaction - Navigation - Scripting - ObservationConnection priority:
Auto-Launch (default, zero-config) — starts Chrome as a child process via
--remote-debugging-pipe, visible as a window, with all flags set for reliable screenshots and keyboard focus.WebSocket (optional) — if you already run Chrome with
--remote-debugging-port=9222, Public Browser connects to that instead. Use this to control your own browser with its extensions and login sessions.
Requirements
Node.js >= 18
Google Chrome, Chromium, or any Chromium-based browser (auto-detected on macOS/Linux/Windows; override with
CHROME_PATH)
Environment Variables
Variable | Values | Default | Description |
|
|
| Auto-launch Chrome if no running instance found |
|
|
| Opt-in headless mode for CI/server environments |
|
|
| CDP debugging port. Non-default values spawn an isolated Chrome instance (separate |
| host |
| CDP host. Alias: |
|
|
| Script API port (needs |
|
|
|
|
| path | — (temp dir) | Directory downloads are written to. Created if missing, never deleted |
|
| — (off) | Report a |
|
|
|
|
| path |
| Per-instance cortex pattern store |
| path | — | Chrome user profile directory (auto-launch only). Alias: |
| path | — | Path to Chrome binary (overrides auto-detection) |
|
| — (disabled) | Opt-in: upload anonymised Cortex patterns to the community endpoint |
| URL |
| Override the telemetry collection endpoint (must be HTTPS) |
Invalid values fail loudly: an unparseable port or naming mode aborts startup
with a named error instead of silently falling back to 9222. Sessions created
through the Node library ignore every variable in this table except
CHROME_PATH and the telemetry pair — see Node Library API.
License
MIT licensed — see LICENSE. Use it however you want, commercially or otherwise.
Contributing
Issues and pull requests welcome at github.com/Silbercue/public-browser.
Privacy
Public Browser runs entirely on your machine. All browser automation happens locally via CDP. The Cortex learning layer stores only structural metadata locally (page types, tool names, content hashes — no URLs, no domains, no page content, no PII). Telemetry is off by default. If you opt in via PUBLIC_BROWSER_TELEMETRY=1, only the same structural metadata is uploaded via HTTPS — the payload is built from an explicit field allowlist to prevent accidental leakage.
Related
Building for iOS too? SilbercueSwift is the same idea for the iOS Simulator.
Links
Available Tools
25 toolsbatch_evaluateA
Visit several URLs in sequence and run the same JS expression on each. For controlled checks across known pages where view_page/run_plan would be too chatty; not for normal reading, clicking or form work.
| Name | Required | Description | Default |
|---|---|---|---|
| urls | Yes | URLs to visit in order | |
| settle_ms | No | Wait in ms after each page load before evaluating | |
| continue_on_error | No | Continue with the remaining URLs if one fails | |
| evaluate_per_page | Yes | JS expression evaluated on each page | |
| timeout_per_page_ms | No | Timeout per page in ms (navigate+settle+evaluate) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations present, the description carries the full burden of behavioral disclosure. It does reveal the core behavioral pattern (sequential navigation, uniform JS expression per page), but it does not disclose that arbitrary JS execution can have side effects or mutate page state, nor what the tool returns for each URL. For a tool that runs JavaScript across multiple pages, that safety-relevant gap is notable.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences with zero filler: the first fronts the action (what the tool does), the second delivers routing guidance (when and when-not). Every clause earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a moderate-complexity tool with fully documented parameters, the description covers purpose and usage completely. The remaining gaps are the return format (no output schema exists to fill it) and unstated side-effect potential of JS evaluation (no annotations exist either). These are meaningful but do not prevent an agent from invoking the tool correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents all five parameters. The description reinforces evaluate_per_page's semantics ('the same JS expression on each') but adds no new parameter-level detail beyond the schema. Baseline 3 is appropriate since the schema does the heavy lifting.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb-resource-action combination: 'Visit several URLs in sequence and run the same JS expression on each.' It also explicitly distances itself from siblings by naming view_page/run_plan and stating what it is not for ('normal reading, clicking or form work'), making it impossible to confuse with the other browsing tools.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives an explicit when-to-use condition ('controlled checks across known pages'), names the alternatives it replaces ('where view_page/run_plan would be too chatty'), and lists exclusions ('not for normal reading, clicking or form work'). An agent can make a correct routing decision with no additional inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
capture_imageA
Pixel-level screenshot (WebP, max 800px, <100KB). Only for canvas or chart content without DOM text, pixel-level rendering or animation checks, or when the user explicitly asks for a screenshot. Returns no refs and reads no text — that is view_page.
| Name | Required | Description | Default |
|---|---|---|---|
| som | No | Overlay numbered labels matching view_page refs (Set-of-Mark) | |
| full_page | No | Capture the full scrollable page, not just the viewport |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries full behavioral disclosure. It states that the tool returns no refs and reads no text, and gives output constraints (WebP, 800px, <100KB). It does not explicitly say 'does not modify the page' but that is strongly implied by the screenshot nature; the disclosed constraints are sufficient for an agent to set expectations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences, front-loaded with the core definition and constraints, followed by usage guidance and sibling differentiation. Every word earns its place; no redundancy or fluff.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple tool with two optional boolean parameters and no output schema, the description covers purpose, constraints, use cases, and key behavioral differences from view_page. A minor gap is that it doesn't explicitly describe the returned image data format, but the WebP and size details imply the output adequately.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%: both 'som' and 'full_page' have clear descriptions in the schema. The tool description does not add extra parameter-level detail, but since the schema already documents both parameters adequately, the baseline score of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description opens with a precise definition: 'Pixel-level screenshot' with concrete format and size constraints (WebP, max 800px, <100KB). It further distinguishes itself from view_page by stating that it returns no refs and reads no text, making the tool's purpose unambiguous and clearly separated from its sibling.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Usage is explicitly scoped: 'Only for canvas or chart content without DOM text, pixel-level rendering or animation checks, or when the user explicitly asks for a screenshot.' It also names the alternative (view_page) for cases involving refs/text, giving the agent clear routing guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
clickA
Click an element by ref, CSS selector, visible text, or viewport x/y (canvas, pixel-precise targets). Dispatches real CDP mouse events. A click that opens a new tab is reported in the response. The DOM diff (NEW/REMOVED/CHANGED) arrives with the next response, or in this one with wait_for_diff: true.
| Name | Required | Description | Default |
|---|---|---|---|
| x | No | Viewport X in px; with y, not ref/selector | |
| y | No | Viewport Y in px; use with x | |
| ref | No | Element ref (preferred) | |
| text | No | Visible text (a11y name); no view_page needed, prefers interactive | |
| selector | No | CSS selector (fallback) | |
| wait_for_diff | No | Wait for the DOM diff before returning (default false, slower) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full transparency burden. It discloses that real CDP mouse events are dispatched, that a click opening a new tab is reported in the response, and that DOM diff results arrive with the next response unless wait_for_diff is set. These are significant behavioral details beyond the schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences with no filler. The first sentence front-loads the tool's purpose and target options; the second and third cover event dispatch and async behavior. Every sentence adds value.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers targeting modes, event behavior, new-tab reporting, and diff timing, which is substantial given the absence of annotations and output schema. It does not explicitly define precedence when multiple target parameters are supplied, though the schema's 'preferred' and 'fallback' labels mitigate that gap.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
All six parameters are fully described in the schema, so the baseline is 3. The description adds useful cross-parameter semantics: it clarifies the relationship between x/y, explains that text targeting works without view_page, and highlights the wait_for_diff latency trade-off.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description names a specific verb (Click) and enumerates the supported target strategies: ref, CSS selector, visible text, and viewport x/y for canvas/pixel-precise targets. This clearly distinguishes the tool from siblings like type, press_key, and scroll.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives strong within-tool usage guidance: ref is preferred, selector is a fallback, text needs no view_page, and x/y is for canvas/pixel-precise targets. It does not explicitly contrast with sibling tools like type or fill_form, but the targeting guidance is clear enough to select the correct mode.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
configure_sessionA
View or set session defaults for recurring parameters (tab, timeout, …). Without params: show current defaults and auto-promote suggestions; autoPromote: true applies them. Set profile BEFORE any browser interaction to launch Chrome with a named profile.
| Name | Required | Description | Default |
|---|---|---|---|
| profile | No | Chrome profile name (list them with: public-browser profiles); restart: true switches mid-session | |
| restart | No | Restart Chrome with the new profile even if running; closes all tabs | |
| defaults | No | Param name → default value; null removes a default | |
| autoPromote | No | Apply all current auto-promote suggestions |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral disclosure burden. It reveals the dual view/set behavior, what autoPromote actually does, and the important ordering constraint that profile changes should happen before browser interactions. It does not discuss persistence or side effects beyond what the schema already documents, but the description provides meaningful behavioral context rather than just restating the tool name.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is only two sentences, yet it communicates the core operation, the no-parameter behavior, the autoPromote effect, and the profile timing constraint. Every clause earns its place with no filler or repetition.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's moderate complexity, four optional parameters, and absence of an output schema, the description covers the essential cases: viewing defaults, applying suggestions, and setting a profile before browser interaction. It could be more explicit about what the returned defaults look like or how the defaults object relates to recurring parameters, but it is sufficient for an agent to invoke the tool correctly in the main scenarios.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already documents all four parameters with 100% coverage, so the baseline is 3. The description adds extra meaning by explaining the zero-parameter call behavior and by specifying that profile must be set before browser interaction, which is not conveyed by the schema's parameter descriptions alone.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description opens with a specific verb-resource pair, 'View or set session defaults,' and clarifies that it handles recurring parameters like tab and timeout. This distinguishes it clearly from the sibling browser-interaction tools, which act on pages or tabs rather than session-level configuration.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It gives concrete usage conditions: calling with no parameters shows current defaults and auto-promote suggestions, setting autoPromote to true applies them, and profile must be set before any browser interaction. It does not explicitly name alternatives or state when not to use the tool, so it doesn't earn a 5, but the guidance is clear and actionable.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
console_logsA
Read collected browser console logs; filter by level (info/warning/error/debug) and/or regex; optionally clear the buffer after reading.
| Name | Required | Description | Default |
|---|---|---|---|
| clear | No | Clear the buffer after reading | |
| level | No | Filter by log level | |
| pattern | No | Regex matched against log text |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description must carry the full disclosure burden. It does so by explicitly labeling the operation as 'Read' and prominently disclosing the optional destructive side effect of clearing the buffer. It could add more detail about buffer source or retention, but the key side effect is clearly exposed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single well-structured sentence packs the main action, the filtering options, and the optional side effect without wordiness. It is front-loaded with the most important information and every phrase earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool has only three optional parameters, no output schema, and no annotations, so the description adequately covers purpose, filters, and the clear flag. Minor gaps around return format and where the logs come from remain, but they are not critical for a tool this simple.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description goes beyond the schema by explaining that 'level' and 'pattern' can be used together as filters ('and/or regex') and that 'clear' is an optional post-read action, which clarifies parameter relationships and intent.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb ('Read') and resource ('collected browser console logs'), then adds filter behavior and an optional clearing side effect. This clearly distinguishes it from the other browser automation siblings by emphasizing a read-only diagnostic purpose.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The purpose is obvious: read logs, apply filters, optionally clear. It doesn't explicitly name alternatives or exclusion conditions, but the context is sufficient because this tool serves a unique diagnostic function among the sibling browser tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
dom_snapshotA
Structured layout data: bounding boxes, computed styles, paint order, colors; refs match view_page. Only for spatial questions view_page cannot answer (is A above B? what color?).
| Name | Required | Description | Default |
|---|---|---|---|
| ref | No | Element ref for a subtree snapshot |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description carries full responsibility. It discloses the kind of data returned and the scope of use, and the data-only framing implies a read-only operation. It doesn't explicitly state that no page mutation occurs or what happens when ref is omitted, but it is reasonably transparent for a snapshot-introspection tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two tightly packed sentences: the first lists the data categories and the cross-tool ref relationship; the second states the exclusive usage condition. No filler, no repetition, and key information is front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a one-parameter tool with no output schema, the description covers the nature of return data, the ref linkage to view_page, and the intended use case. A small gap is the unspecified default scope when ref is omitted, but the schema's 'subtree snapshot' partially addresses that. Overall, sufficient for correct invocation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already documents the only parameter (ref) at 100% coverage, so baseline is 3. The description adds genuinely useful context by noting 'refs match view_page', telling the agent that refs are shared with the sibling tool and clarifying how to populate the parameter. This exceeds the schema alone.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool's resource and function: it provides structured layout data including bounding boxes, computed styles, paint order, and colors. It explicitly distinguishes itself from view_page by naming the exact spatial questions it answers, so an agent can differentiate it from siblings without inspecting schemas.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly says the tool is 'only for spatial questions view_page cannot answer' and provides concrete examples ('is A above B? what color?'). This is a clear when-to-use instruction and also implies when to prefer view_page, leaving nothing to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
downloadA
Wait for pending downloads or list this session's downloaded files. Downloads start by themselves when you click a download link or open a file URL (PDF, CSV, …); this tool never triggers them. download() waits for a pending download to finish; download({ action: 'list' }) returns at once.
| Name | Required | Description | Default |
|---|---|---|---|
| action | No | status waits for pending downloads; list: history, never waits (use for polling) | status |
| settle | No | Ms to wait for a download to START before reporting none — Chrome fires downloadWillBegin a few ms after the click; 0 = instant | |
| timeout | No | Max wait in ms for pending downloads |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It clearly discloses that the tool never triggers downloads and that the default call waits while list returns immediately. It could additionally describe what happens when no download is pending or what the return payload looks like, but the schema partially covers timeouts and settling.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences with no filler: the first states the core purpose, the second explains the triggering mechanism, and the third shows the behavioral difference between modes. The most important information is front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool has no output schema and no annotations, but the description plus the rich parameter schema gives the agent enough to call it correctly. It explains what the tool does, when to use it, and which mode to choose for waiting vs. listing, though an explicit note about the return format would make it fully complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, with detailed descriptions for action, settle, and timeout, including defaults and enum meanings. The description adds a useful call-form example but not semantic information beyond what the schema already provides, so baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb and resource: 'Wait for pending downloads or list this session's downloaded files.' It also clearly distinguishes itself from triggering tools by saying 'this tool never triggers them,' which prevents confusion with click/navigate/file actions.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly tells the agent when to use the tool: after a download link is clicked or a file URL is opened, and explains that downloads are triggered by user/browser actions, not by this tool. It also distinguishes the two modes: status waits, list returns immediately for polling.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
dragA
Drag via native CDP mouse events. Works for CSS-driven drag: slider thumbs, resize handles, text selection, mouse-based reorder lists (SortableJS in mouse mode). NOT for the HTML5 Drag&Drop API (draggable=true with dragstart/drop listeners, React DnD HTML5Backend, Vuedraggable, ng2-dnd) — that needs Input.dispatchDragEvent. Source: from_ref/from_selector or from_x+from_y; target: to_ref/to_selector or to_x+to_y.
| Name | Required | Description | Default |
|---|---|---|---|
| to_x | No | Target viewport X in px (with to_y) | |
| to_y | No | Target viewport Y in px | |
| steps | No | Native mouseMoved events between press and release; minimum 5 | |
| from_x | No | Source viewport X in px (with from_y) | |
| from_y | No | Source viewport Y in px | |
| to_ref | No | Target element ref | |
| from_ref | No | Source element ref | |
| to_selector | No | Target CSS selector | |
| from_selector | No | Source CSS selector |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Since no annotations are provided, the description carries the full burden of behavioral disclosure. It reveals the low-level mechanism (native CDP mouse events), the interaction types it can drive, and its exclusions. It stops short of describing side effects like cursor movement or whether the action waits for animations to settle, but it is substantially transparent for a drag operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is compact but information-dense. The first sentence states the purpose and supported drag types; the second states exclusions and source/target options. Every clause adds value, though the long list of excluded frameworks is slightly verbose. Still, it is well front-loaded and efficient.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with 9 parameters, no annotations, and no output schema, the description covers the essential guidance: what it does, what it cannot do, and how to specify source and target. The 'steps' parameter is already documented in the schema. The only minor gap is that it does not mention what happens after the drag completes (e.g., waiting for resulting state), but overall it is sufficiently complete for an agent to invoke it correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
All 9 parameters have schema descriptions, so the schema already provides individual meaning. The description adds valuable higher-level semantics by grouping source parameters as 'from_ref/from_selector or from_x+from_y' and target parameters similarly, clarifying exclusive pairings that the schema alone does not express. This meaningfully helps an agent construct valid parameter combinations.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description opens with a specific verb and resource: 'Drag via native CDP mouse events.' It then enumerates concrete use cases (slider thumbs, resize handles, text selection, mouse-based reorder lists) and explicitly distinguishes itself from the HTML5 Drag&Drop API. This makes the tool's purpose unmistakable and clearly separates it from sibling input tools like click, type, and scroll.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly states when NOT to use this tool ('NOT for the HTML5 Drag&Drop API') and names the alternative mechanism ('that needs Input.dispatchDragEvent'). It also lists the scenarios it DOES support, giving clear conditions for selection. No inference is required to decide whether this tool fits a given drag task.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
evaluateA
Run JavaScript in the page. Good uses: computation, style mutations (.style.X = ..., classList), shadow-root traversal, in-page fetch(), app-specific side effects no dedicated tool covers. Scope is shared between calls; top-level const/let/class are wrapped in an IIFE. If/else blocks may return undefined — use a ternary or an explicit return.
| Name | Required | Description | Default |
|---|---|---|---|
| expression | Yes | JavaScript code to execute in the page context | |
| await_promise | No | Whether to await Promise results |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden, and it delivers: it warns that scope is shared between calls, top-level declarations are wrapped in an IIFE, and if/else blocks may return undefined, recommending ternaries or explicit returns. This is meaningful execution behavior an agent needs to predict results. It omits error handling and return-format details, but the provided traps are valuable.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three compact sentences carry high signal: the primary purpose, a curated list of good uses, and the critical behavioral caveats. Every sentence adds value, and the most important facts are front-loaded. It is appropriately concise for the complexity involved.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a generic JS-evaluation tool with two simple parameters and no output schema, the description covers purpose, usage scope, and key execution quirks. Missing are default return behavior and error semantics, but the given detail is enough for most agent decisions. The tool is not so complex that every nuance needs explanation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%: both 'expression' and 'await_promise' have descriptive schema text. The description adds no parameter-level information, so it earns the baseline score of 3. No gaps in parameter understanding remain because the schema already explains them.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description begins with a clear verb and resource: 'Run JavaScript in the page.' It then enumerates specific good-use categories (computation, style mutations, shadow-root traversal, in-page fetch, app-specific side effects) that distinguish it from sibling tools like click, type, and dom_snapshot. It also signals it is the fallback when 'no dedicated tool covers' a case, which helps an agent choose it correctly.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives explicit use cases and implies dedicated tools take precedence ('no dedicated tool covers'). It does not explicitly list which sibling to use instead for common actions, but the provided good uses create a clear boundary. The guidance is usable and context-rich, though it could be stronger by naming alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
file_uploadB
Upload file(s) to an identified by ref or CSS selector; file paths must be absolute.
| Name | Required | Description | Default |
|---|---|---|---|
| ref | No | Element ref of the file input | |
| path | Yes | Absolute path(s) of the file(s) to upload | |
| selector | No | CSS selector of the file input; needed for hidden inputs (display:none, off-screen), which have no ref |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
There are no annotations, so the description carries the full burden of behavioral disclosure. It only restates the upload action and the absolute-path requirement, which is already in the schema. It does not disclose side effects, event behavior, handling of hidden inputs, or what happens on failure.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single well-structured sentence that front-loads the action and target, then adds the critical path constraint. No wasted words.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The schema fully documents all three parameters, so a valid call can be constructed. However, with no annotations and no output schema, the description does not clarify behavioral expectations, error conditions, or when selector is needed versus ref, leaving some contextual gaps for an agent.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description adds little beyond the schema: it mentions ref/CSS selector and absolute paths, both of which are already documented in the parameter descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb ('Upload') and a clear resource ('<input type="file">'), and identifies targeting via ref or CSS selector. It is clear and distinct from siblings like click/type, but it does not explicitly name an alternative or contrast itself with fill_form, so it stops short of a top-tier differentiation.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The usage is implied: use this tool when uploading files to a file input. The absolute-path requirement is a useful prerequisite, but there is no explicit guidance about when to prefer this over fill_form/type or any exclusion criteria.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
fill_formA
Fill a whole form in one call: text inputs, (by value or visible label), checkboxes (boolean) and radio buttons. One round-trip; partial errors do not abort and each field reports its own status. On per-field errors call view_page and retry the failing fields.
| Name | Required | Description | Default |
|---|---|---|---|
| fields | Yes | Each needs ref or selector plus value |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it delivers meaningful behavioral details: one round-trip, partial errors do not abort, each field reports its own status, and select values can be supplied by value or visible label. These traits go beyond a generic 'fill form' description, though side effects or clearing behavior are not addressed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is three tight sentences with no filler. The scope and supported input types are front-loaded, followed by behavioral guarantees and the error-retry instruction. Every clause earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a single-parameter tool with no annotations and no output schema, the description gives enough to invoke the tool correctly and recover from failures. It covers supported element types, value semantics, non-aborting partial failures, and a retry path. The only notable gap is the exact shape of per-field status reporting.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already covers parameter structure with 100% description coverage, so the baseline is 3. The description adds value by explaining type-to-control mapping: booleans for checkboxes/radio buttons, string for text/select, and select matching by value or visible label. This clarifies semantics beyond the raw schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states a specific action ('Fill a whole form in one call') and enumerates the supported input types: text inputs, select, checkboxes, and radio buttons. It distinguishes fill_form from siblings like click and type by emphasizing the batch, one-round-trip behavior.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description conveys when to use the tool: for filling an entire form in one call rather than field-by-field typing/clicking. It also gives an explicit recovery path for per-field errors: call view_page and retry failing fields. It stops short of listing scenarios where fill_form should not be used, but the guidance is still actionable.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
handle_dialogA
Configure handling of alerts, confirms and prompts. Set it BEFORE triggering the action that opens the dialog. Uses CDP Page.javascriptDialogOpening, so it works even while the dialog blocks all JS.
| Name | Required | Description | Default |
|---|---|---|---|
| text | No | Text entered into prompt dialogs (with action accept) | |
| action | Yes | accept or dismiss the next dialog; get_status: pending ones |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It discloses an important implementation trait: it uses CDP Page.javascriptDialogOpening, so it functions even while the dialog blocks all JavaScript. It also warns that configuration must happen before the triggering action. Minor gaps remain, such as whether the handler persists across dialogs, but the provided behavioral detail is meaningful.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two compact sentences with no filler. The purpose is front-loaded, and the critical timing caveat and CDP mechanism each earn their place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple two-parameter tool with full schema coverage, the description is largely complete: it explains purpose, timing, and mechanism. The only missing piece is the exact shape of get_status output, but the action is simple enough that the schema enum plus 'pending ones' provides adequate guidance.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the input schema already fully documents both parameters and the enum values. The description adds no additional parameter meaning, which is acceptable given the baseline for fully covered schemas.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb ('Configure') and a precise resource ('handling of alerts, confirms and prompts'), clearly distinguishing this from the browser-interaction siblings like click, type, and navigate. No other sibling targets JavaScript dialogs.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives clear usage context: set this before triggering the action that opens the dialog, and it works even when the dialog blocks JS. It does not explicitly enumerate alternatives or exclusions, but no sibling tool handles dialogs, so the routing is still clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
network_monitorA
Capture network requests via CDP, including those the page issues itself. Workflow: start → trigger the action → get(pattern: 'api').
| Name | Required | Description | Default |
|---|---|---|---|
| action | Yes | start recording | get results | stop: return and clear | |
| filter | No | 'failed': only HTTP >= 400 or network errors | |
| pattern | No | Regex for request URLs |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It discloses a non-obvious behavior: the tool captures requests the page itself issues, not just externally visible traffic. The workflow also communicates the stateful lifecycle of start/get/stop. It does not detail return payload shape or repeated-start reset behavior, but schema covers the stop semantics. Overall, it adds meaningful behavioral context beyond the structured fields.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences with no filler. The first sentence states the core purpose and scope; the second gives the essential workflow. Every part contributes meaning, and the most important information is front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a stateful tool with three parameters and no output schema, the description provides the essential lifecycle and an example call. However, it does not explain what the get action returns (e.g., status codes, headers, timing data), and there is no guidance on repeated start calls. Since no output schema exists, this missing return-format information leaves the agent somewhat uncertain after invocation. Adequate but not fully complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description adds value by showing how the pattern parameter is intended to be used in the workflow ('get(pattern: "api")'), which illustrates parameter application rather than just listing definitions. This minimal but useful addition justifies slightly above baseline.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb and resource: 'Capture network requests via CDP'. It also refines the scope with 'including those the page issues itself', which clearly distinguishes what is captured. No sibling tool overlaps with this function, so the purpose is unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides a clear workflow: 'start → trigger the action → get(pattern: "api")', which tells an agent the order of operations and how to use the pattern parameter. It does not explicitly mention alternatives or exclusions, but no sibling tool is a natural alternative for network monitoring, so this is acceptable.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
observeA
Watch an element for changes instead of polling with MutationObserver/setInterval code in evaluate. collect: record text/attribute changes for 'duration' ms. until: wait for a condition, then optionally click at once (then_click). click_first fires the triggering action after the observer is armed, so nothing is missed.
| Name | Required | Description | Default |
|---|---|---|---|
| until | No | JS expression checked on each change, 'el' is the element, e.g. el.textContent === '8' | |
| collect | No | text (textContent) | attributes | all | text |
| timeout | No | Max observation time in ms (max 25000) | |
| duration | No | Collect window in ms (default 5000); exclusive with until | |
| interval | No | Polling fallback interval in ms | |
| selector | Yes | CSS selector or ref of the element to observe | |
| then_click | No | Selector or ref to click immediately when until holds | |
| click_first | No | Selector or ref to click once the observer is armed |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full disclosure burden, and it delivers meaningfully: it reveals two distinct operational modes (collect and until), the click-ordering guarantee ('click_first fires the triggering action after the observer is armed, so nothing is missed'), and the optional then_click behavior. It stops short of noting the internal polling fallback behind the interval parameter, though the schema documents that parameter.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences with the main purpose front-loaded in sentence one, followed by compact mode explanations. Every sentence earns its place; the 'so nothing is missed' clause captures an important ordering guarantee in four words without padding.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers the two execution modes and the click behaviors well, but the tool has no output schema and the description never states what the tool returns after a collect window or when an until condition fires. Constraint details like duration/until exclusivity and the polling-fallback behavior are left entirely to the schema. For an 8-parametter tool with zero annotations, this is adequate but not complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, giving a baseline of 3, and the description adds genuine value on top of the schema: it connects collect to duration, until to then_click, and clarifies the intent of click_first ('fires the triggering action after the observer is armed'). This conceptual grouping makes the parameter model understandable in a way the flat per-parameter schema descriptions alone do not.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific action (watch an element for changes) on a specific resource (a DOM element via selector), and immediately distinguishes itself from the sibling evaluate tool ('instead of polling with MutationObserver/setInterval code in evaluate'). A new agent can tell what this tool does and how it differs from evaluate without opening the schema.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The opening line gives a clear when-to-use signal: prefer this tool over hand-written MutationObserver/setInterval polling inside evaluate, which is a concrete alternative. However, the 'until' mode functionally overlaps with the sibling wait_for tool, and the description never mentions that alternative or states when not to use observe, so the routing guidance is incomplete.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
press_keyA
Press a key or shortcut (Enter, Escape, Tab, arrows, Ctrl+K). Optionally focus an element first via ref or selector.
| Name | Required | Description | Default |
|---|---|---|---|
| key | Yes | Key to press, e.g. 'Enter'; printable chars as-is | |
| ref | No | Element ref to focus first | |
| selector | No | CSS selector to focus first | |
| modifiers | No | Modifier keys held during the press |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
There are no annotations, so the description carries the burden of behavioral disclosure. It states the core action (pressing a key or shortcut) and the optional focus-first behavior, which is useful. It does not disclose details like whether the key event is dispatched natively, whether modifiers are held during the press, or whether any wait/retry behavior occurs, but the description is not misleading.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, tightly worded sentence that front-loads the core action and then adds the optional focusing detail. No filler or redundant information is present.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a relatively simple keyboard-action tool with a fully described schema, the description covers the essential usage and behavior. It lacks an explicit note about return values or post-press page effects, but the tool's low complexity and complete parameter documentation make the definition largely sufficient.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents key, ref, selector, and modifiers. The description adds value with concrete key examples and clarifies the optional focus-first usage of ref/selector, but it does not meaningfully enrich parameter semantics beyond what the schema provides.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('Press') and a clear resource ('a key or shortcut'), with concrete examples like Enter, Escape, Tab, arrows, and Ctrl+K. This makes the tool's purpose unambiguous and distinguishes it from sibling tools like click (mouse action) or type (text input) without needing to open the schema.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies when to use the tool through examples of keyboard shortcuts and key presses, and mentions the optional focus-first behavior via ref or selector. However, it does not explicitly state when to prefer press_key over siblings like type or click, nor does it provide exclusions or alternative routing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
run_planA
Batch the next 2+ known actions (click, type, scroll, view_page chains) here instead of N separate calls: a sequence of tool steps, executed server-side in one call. Variables via vars and saveAs ($name), conditions (if), suspend/resume to ask the agent mid-plan, errorStrategy abort | continue | capture_image, and parallel groups per tab: parallel: [{ tab, steps }].
| Name | Required | Description | Default |
|---|---|---|---|
| vars | No | Initial variables, available as $name | |
| steps | No | Tool steps to run in order | |
| resume | No | Resume a suspended plan | |
| parallel | No | Tab groups to run in parallel | |
| use_operator | No | Operator mode (rule engine + micro-LLM); needs the executeOperator hook | |
| errorStrategy | No | abort stops at the first error; continue runs all steps; capture_image screenshots, then aborts | abort |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It discloses server-side execution, variable flow, conditional steps, suspend/resume behavior, error strategies, and parallel groups. It does not cover partial-failure side effects or return values, but the disclosed traits are substantial and accurate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is dense but efficient, conveying all major capabilities in a single compact sentence. It could benefit from a structured breakdown, but every phrase carries meaning and the core purpose is front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a complex tool with nested objects and no output schema, the description covers the main operational dimensions: what it batches, how variables work, control flow, suspension, error handling, and parallelism. It does not describe the plan result or how to obtain the planId after suspension, though those are partially in the schema.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description adds a useful high-level mapping of features to concepts like $name, if, suspend/resume, errorStrategy, and parallel groups, but it does not materially deepen parameter details beyond what the schema already documents.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool batches multiple known actions into one server-side call, explicitly naming click, type, scroll, and view_page chains. This directly distinguishes it from the individual action sibling tools and conveys its orchestration role.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It says to use this 'instead of N separate calls' for '2+ known actions,' which gives a concrete condition for choosing it over individual action tools. It does not explicitly say when not to use it, but the focus on known actions implies uncertain or exploratory flows should be done step-by-step.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
scrollA
Scroll the page, a container, or an element into view. Reports the position and content growth (scrollHeight delta — detects lazy-loaded content) and handles settle timing. Use container_ref/container_selector plus direction to scroll inside a container.
| Name | Required | Description | Default |
|---|---|---|---|
| ref | No | Element ref to scroll into view | |
| amount | No | Pixels per scroll (default 500); only with direction | |
| selector | No | CSS selector to scroll into view | |
| direction | No | up or down (default down); used when no ref/selector | |
| container_ref | No | Scrollable container ref (scrolls it, not the page) | |
| container_selector | No | Scrollable container CSS selector |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It covers important runtime behavior: it reports position, detects content growth via scrollHeight delta (useful for lazy-loaded content), and handles settle timing. It does not mention potential side effects or failure modes, but for a scrolling action this is reasonably transparent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences, front-loaded with the core purpose, and every clause adds information: scope, behavioral reports, lazy-load detection, settle handling, and container-specific usage. There is no filler or redundant restating of the tool name.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool has six parameters, no required fields, no annotations, and no output schema. The description covers target selection, container behavior, and what is reported, which is enough to invoke it correctly. It could add explicit return structure or failure behavior, but those would be improvements rather than critical gaps.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description adds value beyond the schema by explaining the relationship between container_ref/container_selector and direction for scrolling inside a container, which clarifies parameter combinations not fully spelled out in the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('Scroll') and explicitly names the resources it operates on: page, container, and element. It further distinguishes itself by mentioning position reporting, content-growth detection, and settle timing, which separates it from navigation or page-view siblings.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives clear operational context: use ref/selector to scroll into view, direction for page scrolling, and container_ref/container_selector plus direction for container scrolling. It does not explicitly name sibling alternatives or exclusion cases, but the usage context is clearly implied.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
set_page_dataA
Write a payload larger than 1 MB into window.__pb_data[key], chunked past the CDP 1 MB message limit. Source: inline (data) or file (absolute path, read as binary). The page reads window.__pb_data[key] (string or ArrayBuffer per encoding) and window.__pb_data[key + '__complete'] === true. Never write one key from parallel calls — they race. Under ~200 KB use evaluate; for a real use file_upload.
| Name | Required | Description | Default |
|---|---|---|---|
| key | Yes | Property name under window.__pb_data (JS identifier, see pattern) | |
| source | Yes | inline: pass data. file: pass an absolute path, read as binary | |
| encoding | No | utf8 (inline default) keeps a string; binary (file default) gives an ArrayBuffer for FileReader/Blob/fetch; base64 keeps the base64 string | |
| chunkSize | No | Raw bytes per chunk before base64 (default 500000; max 700000) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it delivers: chunking behavior, the page-side contract (`__complete` flag), encoding-dependent consumer types (string vs ArrayBuffer), and a concurrency race warning. This is a high level of disclosure for a tool with no structured hints.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Every sentence carries useful information and the core purpose is front-loaded. It is slightly denser than necessary and partially repeats source options already in the schema, but there is no filler or padding.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description thoroughly covers input modes, page behavior, safety, and alternatives. However, it never states what the tool call returns or whether it resolves after chunks are sent versus after the page sets `__complete`. With no output schema, this is a meaningful gap for an agent deciding how to observe completion.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description adds meaningful context on top: inline vs file source semantics, binary reading for files, and how encoding affects whether the page receives a string or ArrayBuffer. This goes beyond the schema's raw type descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb ('Write'), a specific target (`window.__pb_data[key]`), and a distinguishing mechanism (chunking past the CDP 1 MB limit). It is clearly differentiated from siblings like `evaluate` and `file_upload`, which are explicitly named as alternatives.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Provides explicit when-to-use guidance: payloads larger than 1 MB. It also names excluded alternatives: use `evaluate` under ~200 KB and `file_upload` for real `<input type=file>` cases. The warning about parallel writes to the same key adds important usage constraint.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
switch_tabA
Open a new tab, switch to a tab by ID (from virtual_desk), or close one. Prefer 'open' over navigate when the user's active tab must stay untouched. Refs from the previous tab are invalid afterwards — call view_page before acting.
| Name | Required | Description | Default |
|---|---|---|---|
| tab | No | Tab ID or 1-based number (switch/close; close: active tab) | |
| url | No | URL for a new tab (open); default about:blank | |
| action | No | open | switch | close | switch |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral disclosure burden. It clearly warns that refs from the previous tab are invalid afterward and tells the agent to call view_page before acting, which is a key side-effect beyond what the schema reveals.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three short sentences deliver all essential guidance with no filler. The main action set is front-loaded, followed by the usage caveat and the critical invalidation warning, each earning its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers the three actions, the source of tab IDs, the open-vs-navigate decision, and the invalid-ref consequence, which is strong for a tool without annotations or an output schema. It could be slightly more explicit about post-open/switch state, but the provided guidance is sufficient for correct invocation in most cases.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description adds meaningful value by specifying that tab IDs come from virtual_desk and by clarifying the open behavior relative to the active tab, going slightly beyond the schema's parameter descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly enumerates three specific operations—open, switch, and close—on tabs, and ties tab IDs to virtual_desk. It is differentiated from navigate by explicitly preferring open when the active tab must stay untouched.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It gives explicit guidance to prefer open over navigate when the active tab must remain unchanged, which is a concrete decision rule. It also instructs that view_page should be called after switching because old refs are invalid, though it does not fully cover when to use alternatives like tab_status.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
tab_statusA
Active tab's cached URL, title, ready state and errors — a cheap mid-workflow sanity check ('did my click navigate?'). Not for tab discovery or page content.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral disclosure burden. It honestly states the data is cached, implying it may not be perfectly live, and characterizes the call as cheap, signaling low cost. It also mentions errors are included, giving useful behavioral context beyond a simple 'get status' phrasing.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences deliver a dense but readable description: what the tool returns, the typical use case, and a clear boundary. Every phrase earns its place, and the most important identifying information is front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a zero-parameter tool with no output schema, the description is complete: it lists the returned fields (URL, title, ready state, errors), the scope (active tab), the performance profile (cheap), and the appropriate use case. Nothing essential is missing for an agent to decide whether and when to invoke it.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool has zero parameters, so there is no parameter semantics burden on the description. The baseline of 4 applies because no parameter documentation is needed and the description appropriately focuses on what the tool returns rather than input details.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly identifies the tool as returning the active tab's cached URL, title, ready state, and errors, which is a specific, concrete resource. It also explicitly distinguishes itself from tools for tab discovery or page content, preventing confusion with siblings like switch_tab, view_page, or dom_snapshot.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives a clear when-to-use scenario: a cheap mid-workflow sanity check, exemplified by 'did my click navigate?'. It also provides an explicit when-not-to-use boundary (not for tab discovery or page content), though it does not name specific alternative tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
typeA
Type text into an input identified by ref or CSS selector. For 2+ fields use fill_form; for special keys (Enter, Escape, Tab, arrows) or shortcuts (Ctrl+K) use press_key.
| Name | Required | Description | Default |
|---|---|---|---|
| ref | No | Element ref (preferred) | |
| text | Yes | Text to type | |
| clear | No | Clear the field first | |
| selector | No | CSS selector (fallback) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure, but it only states the action and target mechanism. It does not disclose whether the field is focused or clicked first, whether text overwrites existing content or appends to the cursor position, what happens when neither ref nor selector is provided, or how multiple matching selectors are handled.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences with no wasted words. The core action is front-loaded, and the sibling-routing guidance is compact and immediately actionable.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Despite a complete schema, this is a mutation-oriented tool with no annotations and no output schema. The description leaves important operational gaps undefined: target resolution when ref/selector is absent, clearing semantics, return/failure behavior, and handling of ambiguous element matches. The sibling routing helps but does not make the description complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents ref, text, clear, and selector meaningfully. The description largely restates 'ref or CSS selector' without adding substantive value beyond what the parameter descriptions already give, landing at the baseline of 3.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description opens with a specific verb and resource: 'Type text into an input identified by ref or CSS selector.' It clearly differentiates itself from sibling tools by explicitly naming fill_form and press_key as the alternatives for multi-field and special-key scenarios.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly states when to use the tool ('Type text into an input') and when not to: 'For 2+ fields use fill_form; for special keys (Enter, Escape, Tab, arrows) or shortcuts (Ctrl+K) use press_key.' It also communicates the ref-preferred, selector-fallback targeting strategy.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
view_pageA
See what is on the page: text plus stable element refs for click/type/fill_form. Default filter 'interactive' lists actionable elements; for paragraphs or table cells call view_page(ref, filter: 'all'). Collapsed containers show as [eXX role, N items] — expand with view_page(ref: 'eXX', filter: 'all').
| Name | Required | Description | Default |
|---|---|---|---|
| ref | No | Element ref for a subtree | |
| depth | No | Tree levels shown; indentation only, hidden sections need a click | |
| filter | No | interactive | all | landmark | visual (bounds, click point, visibility) | interactive |
| max_tokens | No | Token budget; content downsampled. Omit for full output |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the burden of behavioral disclosure. It discloses that the output includes stable refs, that collapsed containers show summaries like '[eXX role, N items]', and that follow-up expansion calls are possible. This is meaningful behavior beyond the schema and helps the agent anticipate output shape.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences, each earning its place: the core purpose comes first, then filter usage, then expansion behavior. There is no filler or redundant restatement of the schema.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For an inspection tool with four optional parameters and no output schema, the description is largely sufficient: it specifies the return content, default behavior, and how to get broader or expanded views. The main gap is the absence of explicit differentiation from sibling inspection tools, but the core calling pattern is fully covered.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so a baseline of 3 applies. The description adds practical meaning by mapping the 'filter' parameter to specific scenarios and explaining how 'ref' is used to expand collapsed subtrees, going beyond the schema's enum descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific action and resource: 'See what is on the page: text plus stable element refs for click/type/fill_form.' It clearly communicates what the tool returns and why it is useful, distinguishing its role from generic page-capture tools even without naming a sibling.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives explicit guidance for variant usage: default filter 'interactive' lists actionable elements, filter 'all' is for paragraphs/table cells, and collapsed containers are expanded via view_page(ref, filter: 'all'). It does not compare against sibling inspection tools like dom_snapshot or observe, but it clearly tells the agent when to adjust the call.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
virtual_deskA
List all open tabs with IDs, URLs and state. Call it first in every session, after a reconnect, or when unsure; reuse a listed tab ID instead of opening duplicates. Cheap, call liberally.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of behavioral disclosure. It clearly indicates a read-only listing operation and adds useful context about cost and call frequency. It does not explain what 'state' includes or what happens if no tabs are open, but for a simple listing tool this is a minor gap.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences with zero fluff: the core purpose is front-loaded, followed by direct usage instructions and a cost hint. Every sentence adds actionable information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a zero-parameter listing tool with no output schema, the description is complete: it states what is listed, when to call it, how to use the results, and how often it may be invoked. No missing information is needed to call or interpret the tool correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool has zero parameters, so the baseline is 4; the description correctly implies no input is needed. It adds no parameter-specific detail because none exists, which is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description begins with a specific verb and resource: 'List all open tabs with IDs, URLs and state.' This clearly distinguishes it from sibling tools like switch_tab or tab_status, which operate on specific tabs or current tab state rather than enumerating everything.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides explicit when-to-use guidance: 'Call it first in every session, after a reconnect, or when unsure.' It also tells the agent to reuse listed tab IDs instead of opening duplicates, and explicitly states the cost profile: 'Cheap, call liberally.'
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
wait_forA
Wait until a condition holds: element visible, page text present, URL match, network idle, or a JS expression true. Prefer condition 'text' over a JS expression for 'has the page said X yet'. assert: true checks once and fails instead of waiting.
| Name | Required | Description | Default |
|---|---|---|---|
| url | No | Substring of the page URL; required for condition 'url' | |
| text | No | Substring of document.body.innerText, case-sensitive; required for condition 'text' | |
| assert | No | Check once, fail if it does not hold; timeout 0, _meta.code 'assertion_failed' | |
| timeout | No | Max wait in ms (default 10000; 0 when assert is true) | |
| selector | No | CSS selector or ref; required for condition 'element' | |
| condition | Yes | element | text | url | network_idle | js | |
| expression | No | Expression that should become true; required for condition 'js' |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral disclosure burden. It explains the core polling-style behavior, the five condition types, and the critical assert mode that checks once and fails instead of waiting. This is meaningful behavioral context beyond the bare schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences with no filler. The main purpose is front-loaded, condition selection guidance is next, and assert behavior is saved for last. Every sentence earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool is moderately complex with seven parameters and no annotations, but the schema covers every parameter and the description covers the core behaviors and condition choices. It could go further by mentioning timeout failure behavior or the relationship to observe, but as paired with the schema it is largely complete for correct invocation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description adds value by advising when to use 'text' instead of a JS expression, which helps an agent choose the correct condition parameter. It also clarifies the semantic effect of assert, adding meaning beyond the parameter descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
Theescription clearly states what the tool does: wait until a condition holds, and enumerates the supported condition types (element, text, URL, network_idle, JS). It is specific about the resource and actions, but does not explicitly differentiate itself from sibling tools such as observe, so it loses the full marks for sibling diistinction.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description provides useful internal selection guidance, particularly preferring condition 'text' over JS expressions for checking page text, and explains the assert: true behavior. However, it does not address when to use wait_for versus a sibling tool such as observe or evaluate, so the usage guidance is partial.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections. Dates show when Glama detected each change.
25 tool updates
v2.10.5- Changed
batch_evaluate7 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / continue_on_error / descriptionPrevious value: -"Continue processing remaining URLs if one fails (default: true)"New value: +"Continue with the remaining URLs if one fails" - changed
Input schema / properties / evaluate_per_page / descriptionPrevious value: -"JavaScript expression to evaluate on each page after it loads"New value: +"JS expression evaluated on each page" - changed
Input schema / properties / settle_ms / descriptionPrevious value: -"Wait time in ms after each page load before evaluating (default: 2000)"New value: +"Wait in ms after each page load before evaluating" - changed
Input schema / properties / timeout_per_page_ms / descriptionPrevious value: -"Timeout per page in ms for the full navigate+settle+evaluate cycle (default: 30000)"New value: +"Timeout per page in ms (navigate+settle+evaluate)" - changed
Input schema / properties / urls / descriptionPrevious value: -"Array of URLs to visit and evaluate sequentially"New value: +"URLs to visit in order"
- Changed
capture_image4 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / full_page / descriptionPrevious value: -"Capture full scrollable page instead of just viewport"New value: +"Capture the full scrollable page, not just the viewport" - changed
Input schema / properties / som / descriptionPrevious value: -"Overlay numbered labels on interactive elements matching view_page ref IDs (Set-of-Mark)"New value: +"Overlay numbered labels matching view_page refs (Set-of-Mark)"
- Changed
click8 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / ref / descriptionPrevious value: -"A11y-Tree element ref (e.g. 'e5') — preferred over selector"New value: +"Element ref (preferred)" - changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector (e.g. '#submit-btn') — fallback when ref is not available"New value: +"CSS selector (fallback)" - changed
Input schema / properties / text / descriptionPrevious value: -"Visible text to match (e.g. 'Submit'). Finds element by name in the A11y tree — no prior view_page needed. Prefers interactive elements (buttons, links)."New value: +"Visible text (a11y name); no view_page needed, prefers interactive" - changed
Input schema / properties / wait_for_diff / descriptionPrevious value: -"When true, wait for the DOM diff synchronously before returning (slower but diff is in this response). Default: false — diff piggybacks on the next tool response."New value: +"Wait for the DOM diff before returning (default false, slower)" - changed
Input schema / properties / x / descriptionPrevious value: -"X coordinate (viewport pixels) — for canvas or pixel-precise clicks. Use with y instead of ref/selector."New value: +"Viewport X in px; with y, not ref/selector" - changed
Input schema / properties / y / descriptionPrevious value: -"Y coordinate (viewport pixels) — for canvas or pixel-precise clicks. Use with x instead of ref/selector."New value: +"Viewport Y in px; use with x"
- Changed
configure_session6 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / autoPromote / descriptionPrevious value: -"If true, apply all current auto-promote suggestions as defaults"New value: +"Apply all current auto-promote suggestions" - changed
Input schema / properties / defaults / descriptionPrevious value: -"Set session defaults. Keys: param names (tab, timeout, etc.). Values: default values. null removes a default."New value: +"Param name → default value; null removes a default" - changed
Input schema / properties / profile / descriptionPrevious value: -"Chrome profile name (e.g. \"Julian\", \"Business\"). Use `public-browser profiles` to list available profiles. With restart: true, can switch profiles mid-session."New value: +"Chrome profile name (list them with: public-browser profiles); restart: true switches mid-session" - changed
Input schema / properties / restart / descriptionPrevious value: -"If true, restart Chrome with the new profile even if the browser is already running. Closes all current tabs."New value: +"Restart Chrome with the new profile even if running; closes all tabs"
- Changed
console_logs4 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / clear / descriptionPrevious value: -"Clear the log buffer after returning results"New value: +"Clear the buffer after reading" - changed
Input schema / properties / pattern / descriptionPrevious value: -"Regex pattern to match against log text"New value: +"Regex matched against log text"
- Changed
dom_snapshot3 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / ref / descriptionPrevious value: -"Element ref (e.g. 'e42') to get subtree snapshot for"New value: +"Element ref for a subtree snapshot"
- Changed
download5 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / action / descriptionPrevious value: -"status: check/wait for pending downloads (waits briefly for one to start, then until it finishes). list: full session history, returns immediately and never waits — use it for polling loops."New value: +"status waits for pending downloads; list: history, never waits (use for polling)" - changed
Input schema / properties / settle / descriptionPrevious value: -"Grace window in ms to wait for a download to START before reporting 'no downloads' (default: 250). Chrome fires downloadWillBegin a few ms after the click that triggers it. Set 0 for an instant check, or use action: 'list' which never waits."New value: +"Ms to wait for a download to START before reporting none — Chrome fires downloadWillBegin a few ms after the click; 0 = instant" - changed
Input schema / properties / timeout / descriptionPrevious value: -"Max wait time in ms for pending downloads (default: 30000)"New value: +"Max wait in ms for pending downloads"
- Changed
drag11 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / from_ref / descriptionPrevious value: -"A11y-Tree source ref (e.g. 'e5')"New value: +"Source element ref" - changed
Input schema / properties / from_selector / descriptionPrevious value: -"CSS selector for source element"New value: +"Source CSS selector" - changed
Input schema / properties / from_x / descriptionPrevious value: -"Source X coord (viewport px) — alternative zu Ref"New value: +"Source viewport X in px (with from_y)" - changed
Input schema / properties / from_y / descriptionPrevious value: -"Source Y coord (viewport px) — alternative zu Ref"New value: +"Source viewport Y in px" - changed
Input schema / properties / steps / descriptionPrevious value: -"Anzahl mouseMoved-Events zwischen press und release (min 5 fuer HTML5-dragover)"New value: +"Native mouseMoved events between press and release; minimum 5" - changed
Input schema / properties / to_ref / descriptionPrevious value: -"A11y-Tree target ref (e.g. 'e7')"New value: +"Target element ref" - changed
Input schema / properties / to_selector / descriptionPrevious value: -"CSS selector for target element"New value: +"Target CSS selector" - changed
Input schema / properties / to_x / descriptionPrevious value: -"Target X coord (viewport px)"New value: +"Target viewport X in px (with to_y)" - changed
Input schema / properties / to_y / descriptionPrevious value: -"Target Y coord (viewport px)"New value: +"Target viewport Y in px"
- Changed
evaluate2 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false
- Changed
file_upload5 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / path / descriptionPrevious value: -"Absolute file path(s) to upload. String for single file, array for multiple files."New value: +"Absolute path(s) of the file(s) to upload" - changed
Input schema / properties / ref / descriptionPrevious value: -"A11y-Tree element ref (e.g. 'e8') — preferred when input is visible in view_page"New value: +"Element ref of the file input" - changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector (e.g. 'input[type=file]') — use this for hidden file inputs (display:none, off-screen). Many React/Vue apps render a visible custom button that triggers a hidden <input type=file>; the hidden input is NOT in the a11y-tree, so ref won't find it. Pass the selector instead."New value: +"CSS selector of the file input; needed for hidden inputs (display:none, off-screen), which have no ref"
- Changed
fill_form7 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / fields / descriptionPrevious value: -"Array of fields to fill. Each field needs ref or selector plus value."New value: +"Each needs ref or selector plus value" - removed
Input schema / properties / fields / items / additionalPropertiesRemoved value: -false - changed
Input schema / properties / fields / items / properties / ref / descriptionPrevious value: -"A11y-Tree element ref (e.g. 'e5') — preferred over selector"New value: +"Element ref (preferred)" - changed
Input schema / properties / fields / items / properties / selector / descriptionPrevious value: -"CSS selector (e.g. '#email') — fallback when ref is not available"New value: +"CSS selector (fallback)" - changed
Input schema / properties / fields / items / properties / value / descriptionPrevious value: -"Value to set: string for text/select, boolean for checkbox/radio, number coerced to string"New value: +"string for text/select, boolean for checkbox/radio; number → string"
- Changed
handle_dialog4 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / action / descriptionPrevious value: -"accept: accept the next dialog, dismiss: dismiss/cancel it, get_status: check pending dialogs"New value: +"accept or dismiss the next dialog; get_status: pending ones" - changed
Input schema / properties / text / descriptionPrevious value: -"Text to enter in prompt dialogs (only used with action: accept)"New value: +"Text entered into prompt dialogs (with action accept)"
- Changed
navigate5 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / action / descriptionPrevious value: -"Navigation action: goto (default), back, or reload"New value: +"goto (default) | back | reload" - changed
Input schema / properties / settle_ms / descriptionPrevious value: -"Extra wait time in ms after page load (default: 500)"New value: +"Extra wait in ms after load (default 500)" - changed
Input schema / properties / url / descriptionPrevious value: -"URL to navigate to (required for goto action)"New value: +"URL to open (required for goto)"
- Changed
network_monitor5 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / action / descriptionPrevious value: -"start: begin recording, get: retrieve recorded requests, stop: return and clear"New value: +"start recording | get results | stop: return and clear" - changed
Input schema / properties / filter / descriptionPrevious value: -"Filter results — 'failed': only requests with HTTP >= 400 or network errors"New value: +"'failed': only HTTP >= 400 or network errors" - changed
Input schema / properties / pattern / descriptionPrevious value: -"Regex pattern to match against request URLs"New value: +"Regex for request URLs"
- Changed
observe10 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / click_first / descriptionPrevious value: -"CSS selector or element ref (e.g. 'e5') to click AFTER the observer is set up but BEFORE collection starts. Use to trigger the changes you want to observe (e.g. 'Start Mutations' button)."New value: +"Selector or ref to click once the observer is armed" - changed
Input schema / properties / collect / descriptionPrevious value: -"What to collect: 'text' for textContent changes, 'attributes' for attribute changes, 'all' for both (default: 'text')"New value: +"text (textContent) | attributes | all" - changed
Input schema / properties / duration / descriptionPrevious value: -"Collect all changes for this many ms, then return them. Mutually exclusive with 'until'. Default: 5000"New value: +"Collect window in ms (default 5000); exclusive with until" - changed
Input schema / properties / interval / descriptionPrevious value: -"Polling interval in ms for change detection fallback (default: 100)"New value: +"Polling fallback interval in ms" - changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector or element ref (e.g. 'e5') of the element to observe"New value: +"CSS selector or ref of the element to observe" - changed
Input schema / properties / then_click / descriptionPrevious value: -"CSS selector or element ref (e.g. 'e5') to click immediately when 'until' condition is met (for timing-critical actions). Only used with 'until'."New value: +"Selector or ref to click immediately when until holds" - changed
Input schema / properties / timeout / descriptionPrevious value: -"Maximum observation time in ms (default: 10000, max: 25000)"New value: +"Max observation time in ms (max 25000)" - changed
Input schema / properties / until / descriptionPrevious value: -"JS expression evaluated on each change — stops when it returns true. Variable 'el' is the observed element. Example: el.textContent === '8'"New value: +"JS expression checked on each change, 'el' is the element, e.g. el.textContent === '8'"
- Changed
press_key6 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / key / descriptionPrevious value: -"Key to press — e.g. 'Enter', 'Escape', 'Tab', 'a', 'ArrowDown', 'F1'. For printable characters use the character itself."New value: +"Key to press, e.g. 'Enter'; printable chars as-is" - changed
Input schema / properties / modifiers / descriptionPrevious value: -"Modifier keys to hold during key press (e.g. ['ctrl', 'shift'] for Ctrl+Shift+key)"New value: +"Modifier keys held during the press" - changed
Input schema / properties / ref / descriptionPrevious value: -"Element ref to focus before pressing key (e.g. 'e5')"New value: +"Element ref to focus first" - changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector to focus before pressing key (e.g. '#search-input')"New value: +"CSS selector to focus first"
- Changed
run_plan24 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - added
Input schema / properties / errorStrategyAdded value: +{ + "default": "abort", + "description": "abort stops at the first error; continue runs all steps; capture_image screenshots, then aborts", + "enum": [ + "abort", + "continue", + "capture_image" + ], + "type": "string" +} - changed
Input schema / properties / parallel / descriptionPrevious value: -"Array of tab groups to execute in parallel across tabs."New value: +"Tab groups to run in parallel" - removed
Input schema / properties / parallel / items / additionalPropertiesRemoved value: -false - changed
Input schema / properties / parallel / items / properties / steps / descriptionPrevious value: -"Steps to execute on this tab"New value: +"Steps for this tab" - changed
Input schema / properties / parallel / items / properties / tab / descriptionPrevious value: -"Tab ID (targetId) to execute steps on"New value: +"Tab ID (targetId)" - removed
Input schema / properties / resume / additionalPropertiesRemoved value: -false - changed
Input schema / properties / resume / descriptionPrevious value: -"Resume a previously suspended plan."New value: +"Resume a suspended plan" - changed
Input schema / properties / resume / properties / answer / descriptionPrevious value: -"Agent's answer to the suspend question"New value: +"Answer to the suspend question" - changed
Input schema / properties / resume / properties / planId / descriptionPrevious value: -"ID of the suspended plan to resume"New value: +"ID of the suspended plan" - changed
Input schema / properties / steps / descriptionPrevious value: -"Array of tool steps to execute sequentially."New value: +"Tool steps to run in order" - removed
Input schema / properties / steps / items / additionalPropertiesRemoved value: -false - changed
Input schema / properties / steps / items / properties / if / descriptionPrevious value: -"Condition expression — step runs only if true. Use $varName for variables. Example: \"$pageTitle === 'Login'\""New value: +"Run the step only if this expression is true, e.g. \"$pageTitle === 'Login'\"" - changed
Input schema / properties / steps / items / properties / params / descriptionPrevious value: -"Parameters for the tool. Use $varName for variable substitution."New value: +"Tool parameters; $name substitutes a variable" - changed
Input schema / properties / steps / items / properties / saveAs / descriptionPrevious value: -"Save step result as variable (accessible via $name in later steps)"New value: +"Save the result as $name for later steps" - removed
Input schema / properties / steps / items / properties / suspend / additionalPropertiesRemoved value: -false - changed
Input schema / properties / steps / items / properties / suspend / descriptionPrevious value: -"Suspend plan at this step to ask the agent a question"New value: +"Pause here to ask the agent a question" - changed
Input schema / properties / steps / items / properties / suspend / properties / condition / descriptionPrevious value: -"Condition expression — suspend AFTER step if true. Uses $varName syntax."New value: +"Suspend after the step if this $-expression is true" - changed
Input schema / properties / steps / items / properties / suspend / properties / context / descriptionPrevious value: -"Context to include: 'capture_image' captures the page"New value: +"capture_image: attach a screenshot" - changed
Input schema / properties / steps / items / properties / suspend / properties / question / descriptionPrevious value: -"Question to ask the agent when suspending"New value: +"Question for the agent" - changed
Input schema / properties / steps / items / properties / tool / descriptionPrevious value: -"Tool name to execute (e.g. 'click', 'type', 'press_key', 'navigate', 'scroll')"New value: +"Tool name" - changed
Input schema / properties / use_operator / descriptionPrevious value: -"Operator mode (rule engine + Micro-LLM). Requires the executeOperator hook to be registered."New value: +"Operator mode (rule engine + micro-LLM); needs the executeOperator hook" - added
Input schema / properties / varsAdded value: +{ + "additionalProperties": {}, + "description": "Initial variables, available as $name", + "type": "object" +}
- Changed
scroll8 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / amount / descriptionPrevious value: -"Pixels to scroll (default: 500). Only used with direction."New value: +"Pixels per scroll (default 500); only with direction" - changed
Input schema / properties / container_ref / descriptionPrevious value: -"Scrollable container ref — scroll this container instead of the page (e.g. 'e10')"New value: +"Scrollable container ref (scrolls it, not the page)" - changed
Input schema / properties / container_selector / descriptionPrevious value: -"Scrollable container CSS selector (e.g. '.sidebar-list')"New value: +"Scrollable container CSS selector" - changed
Input schema / properties / direction / descriptionPrevious value: -"Scroll direction (when no ref/selector given). Default: down"New value: +"up or down (default down); used when no ref/selector" - changed
Input schema / properties / ref / descriptionPrevious value: -"Element ref to scroll into view (e.g. 'e42')"New value: +"Element ref to scroll into view" - changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector to scroll into view (e.g. '#item-30')"New value: +"CSS selector to scroll into view"
- Changed
set_page_data7 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / chunkSize / descriptionPrevious value: -"Raw bytes per chunk before base64 encoding. Default 500_000 (~670 KB base64, safe under CDP's 1 MB-per-message limit). Capped at 700_000 (~933 KB base64) to leave safety margin."New value: +"Raw bytes per chunk before base64 (default 500000; max 700000)" - changed
Input schema / properties / encoding / descriptionPrevious value: -"Encoding interpretation. 'utf8' (default for inline) keeps the data as a string. 'binary' (default for file) decodes to ArrayBuffer in the page so apps can pass it to FileReader / Blob / fetch body. 'base64' keeps the base64 string as-is (the page can decode it itself)."New value: +"utf8 (inline default) keeps a string; binary (file default) gives an ArrayBuffer for FileReader/Blob/fetch; base64 keeps the base64 string" - changed
Input schema / properties / key / descriptionPrevious value: -"Property name under window.__pb_data (JS identifier — letters, digits, underscore; cannot start with digit)"New value: +"Property name under window.__pb_data (JS identifier, see pattern)" - changed
Input schema / properties / source / anyOfPrevious value: -[ - { - "additionalProperties": false, - "properties": { - "data": { - "description": "The payload as a string (base64 or utf-8)", - "type": "string" - }, - "type": { - "const": "inline", - "type": "string" - } - }, - "required": [ - "type", - "data" - ], - "type": "object" - }, - { - "additionalProperties": false, - "properties": { - "path": { - "description": "Absolute file path — the server reads the file as binary", - "type": "string" - }, - "type": { - "const": "file", - "type": "string" - } - }, - "required": [ - "type", - "path" - ], - "type": "object" - } -]New value: +[ + { + "properties": { + "data": { + "description": "Payload string (base64 or utf-8)", + "type": "string" + }, + "type": { + "const": "inline", + "type": "string" + } + }, + "required": [ + "type", + "data" + ], + "type": "object" + }, + { + "properties": { + "path": { + "description": "Absolute file path", + "type": "string" + }, + "type": { + "const": "file", + "type": "string" + } + }, + "required": [ + "type", + "path" + ], + "type": "object" + } +] - changed
Input schema / properties / source / descriptionPrevious value: -"Where to read the payload from. type 'inline' → pass `data` as a string. type 'file' → pass absolute `path`; the server reads the file as binary."New value: +"inline: pass data. file: pass an absolute path, read as binary"
- Changed
switch_tab5 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / action / descriptionPrevious value: -"Action: open (new tab), switch (to existing tab, default), close (close tab)"New value: +"open | switch | close" - changed
Input schema / properties / tab / descriptionPrevious value: -"Tab ID or tab number (1-based index, e.g. '2') to switch to or close (defaults to active tab for close)"New value: +"Tab ID or 1-based number (switch/close; close: active tab)" - changed
Input schema / properties / url / descriptionPrevious value: -"URL to navigate to (for open action, defaults to about:blank)"New value: +"URL for a new tab (open); default about:blank"
- Changed
tab_status1 field changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#"
- Changed
type6 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / clear / descriptionPrevious value: -"Clear existing field content before typing (default: false)"New value: +"Clear the field first" - changed
Input schema / properties / ref / descriptionPrevious value: -"Element reference from view_page (e.g. 'e12') — preferred over selector"New value: +"Element ref (preferred)" - changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector as fallback (e.g. 'input[name=email]')"New value: +"CSS selector (fallback)" - changed
Input schema / properties / text / descriptionPrevious value: -"Text to type into the element"New value: +"Text to type"
- Changed
view_page6 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / depth / descriptionPrevious value: -"Nesting depth — how many tree levels to display (default: 3). Controls indentation, not visibility. Hidden sections (display: none) require clicking tabs/buttons to reveal."New value: +"Tree levels shown; indentation only, hidden sections need a click" - changed
Input schema / properties / filter / descriptionPrevious value: -"Filter mode: interactive (default), all, landmark, or visual (adds bounds/click/visibility)"New value: +"interactive | all | landmark | visual (bounds, click point, visibility)" - changed
Input schema / properties / max_tokens / descriptionPrevious value: -"Token budget — page content is automatically downsampled to fit. Omit for full output."New value: +"Token budget; content downsampled. Omit for full output" - changed
Input schema / properties / ref / descriptionPrevious value: -"Element ref (e.g. 'e5') to get subtree for"New value: +"Element ref for a subtree"
- Changed
virtual_desk1 field changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#"
- Changed
wait_for9 fields changed- removed
Input schema / $schemaRemoved value: -"http://json-schema.org/draft-07/schema#" - removed
Input schema / additionalPropertiesRemoved value: -false - changed
Input schema / properties / assert / descriptionPrevious value: -"Assert instead of wait: check the condition once and fail if it does not hold (default timeout becomes 0). Failures carry _meta.code = 'assertion_failed'."New value: +"Check once, fail if it does not hold; timeout 0, _meta.code 'assertion_failed'" - changed
Input schema / properties / condition / descriptionPrevious value: -"What to wait for: element visibility, visible page text, the URL, network idle, or a JS expression returning true"New value: +"element | text | url | network_idle | js" - changed
Input schema / properties / expression / descriptionPrevious value: -"JavaScript expression that should evaluate to true — required when condition is 'js'"New value: +"Expression that should become true; required for condition 'js'" - changed
Input schema / properties / selector / descriptionPrevious value: -"CSS selector or element ref (e.g. 'e5') — required when condition is 'element'"New value: +"CSS selector or ref; required for condition 'element'" - changed
Input schema / properties / text / descriptionPrevious value: -"Substring of the page's visible text — required when condition is 'text'. Case-sensitive; matches document.body.innerText, i.e. what a reader sees."New value: +"Substring of document.body.innerText, case-sensitive; required for condition 'text'" - changed
Input schema / properties / timeout / descriptionPrevious value: -"Maximum wait time in milliseconds (default: 10000, or 0 when assert is true)"New value: +"Max wait in ms (default 10000; 0 when assert is true)" - changed
Input schema / properties / url / descriptionPrevious value: -"Substring of the page URL — required when condition is 'url'"New value: +"Substring of the page URL; required for condition 'url'"
1 tool update
v2.10.1- Changed
configure_session1 field changed- added
Input schema / properties / restartAdded value: +{ + "description": "If true, restart Chrome with the new profile even if the browser is already running. Closes all current tabs.", + "type": "boolean" +}
2 tool updates
v2.10.0- Changed
download2 fields changed- changed
Input schema / properties / action / descriptionPrevious value: -"status: check/wait for pending downloads, list: show all session downloads"New value: +"status: check/wait for pending downloads (waits briefly for one to start, then until it finishes). list: full session history, returns immediately and never waits — use it for polling loops." - added
Input schema / properties / settleAdded value: +{ + "default": 250, + "description": "Grace window in ms to wait for a download to START before reporting 'no downloads' (default: 250). Chrome fires downloadWillBegin a few ms after the click that triggers it. Set 0 for an instant check, or use action: 'list' which never waits.", + "type": "number" +}
- Changed
wait_for7 fields changed- added
Input schema / properties / assertAdded value: +{ + "default": false, + "description": "Assert instead of wait: check the condition once and fail if it does not hold (default timeout becomes 0). Failures carry _meta.code = 'assertion_failed'.", + "type": "boolean" +} - changed
Input schema / properties / condition / descriptionPrevious value: -"What to wait for: element visibility, network idle, or JS expression returning true"New value: +"What to wait for: element visibility, visible page text, the URL, network idle, or a JS expression returning true" - changed
Input schema / properties / condition / enumPrevious value: -[ - "element", - "network_idle", - "js" -]New value: +[ + "element", + "text", + "url", + "network_idle", + "js" +] - added
Input schema / properties / textAdded value: +{ + "description": "Substring of the page's visible text — required when condition is 'text'. Case-sensitive; matches document.body.innerText, i.e. what a reader sees.", + "type": "string" +} - removed
Input schema / properties / timeout / defaultRemoved value: -10000 - changed
Input schema / properties / timeout / descriptionPrevious value: -"Maximum wait time in milliseconds (default: 10000)"New value: +"Maximum wait time in milliseconds (default: 10000, or 0 when assert is true)" - added
Input schema / properties / urlAdded value: +{ + "description": "Substring of the page URL — required when condition is 'url'", + "type": "string" +}
25 tool updates
v2.7.0- First observed
batch_evaluate - First observed
capture_image - First observed
click - First observed
configure_session - First observed
console_logs - First observed
dom_snapshot - First observed
download - First observed
drag - First observed
evaluate - First observed
file_upload - First observed
fill_form - First observed
handle_dialog - First observed
navigate - First observed
network_monitor - First observed
observe - First observed
press_key - First observed
run_plan - First observed
scroll - First observed
set_page_data - First observed
switch_tab - First observed
tab_status - First observed
type - First observed
view_page - First observed
virtual_desk - First observed
wait_for
TDQS
Most tools map cleanly to distinct browser capabilities such as viewing, clicking, typing, scrolling, downloading, and evaluating JS. A few pairs like observe vs wait_for and view_page vs dom_snapshot have some conceptual overlap, but the descriptions do a good job of drawing boundaries.
Names are consistently lowercase and snake_case, but the pattern is mixed: single verbs like click, type, and scroll sit alongside verb_noun names like view_page and fill_form, and noun-style names like virtual_desk, tab_status, and network_monitor. The set is readable but not stylistically uniform.
25 tools is right at the heavy end of a reasonable browser-automation surface. Each tool addresses a legitimate need, but the count feels large, especially with separate tools for screenshots, DOM snapshots, console logs, network monitoring, and evaluate-style operations.
The toolset covers the full browser workflow: tab and navigation management, DOM reading, interaction, forms, waits, dialogs, uploads, downloads, network/console diagnostics, and JavaScript execution. Minor gaps like cookie/localStorage management, explicit frame switching, and hover could cause workarounds but do not block realistic tasks.
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