web_techstack

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, and it does so richly. It describes the default browser strategy, the auto-escalation behavior, the fallback to DNS-based signals when a fetch completely fails, the automatic www./plain-HTTP retry, and the semantics of `reachable` and `is_infrastructure`. It also explicitly labels results as 'directional, not exhaustive', which is valuable calibration for an agent.

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 long due to a comprehensive enumeration of covered technologies (frameworks, CMSs, analytics, CDNs, etc.), but that list is genuinely useful for an agent deciding whether this tool can answer a specific tech-stack question. The structure is logical: purpose, return shape, coverage areas, fetch strategies, limitations, and special result fields. It is thorough rather than wasteful, though a more condensed coverage summary would have been slightly tighter.

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 absence of an output schema and the shallow input schema, the description is remarkably complete. It explains the shape of `technologies` (categories, confidence, version, evidence), documents `unmatched_evidence`, `is_infrastructure`, `reachable`, and `failure_reason`, and clarifies edge cases like DNS-only partial population. An agent would know what to pass and what to expect back.

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 input schema only defines a `request` object with the terse description 'Target URL (and optional render strategy)'. The tool description substantially compensates by explaining what `render` can be ('browser', 'auto', 'http'), what each strategy means, and which one is the default. It does not explicitly spell out the exact nested property names (e.g., `url`, `render`) inside the `request` object, but the intent is inferable from the description and the schema's container-level hint.

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 'Tech stack — detect what a website is built with' and then specifies a concrete verb ('fetches and fingerprints') on a concrete resource ('a public URL'). It names the analogy to BuiltWith / Wappalyzer and enumerates the broad categories it covers, making the tool's function unambiguous and distinguishable from the many sibling tools in this catalog.

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 clearly indicates this tool is for tech-stack detection and provides context on when to use each fetch strategy ('browser', 'auto', 'http') with tradeoffs. It also states an exclusion ('Only public pages are supported') and instructs the agent to respect terms of use and robots directives. However, it does not explicitly name alternative sibling tools or say when NOT to use this tool in favor of another.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.