List page elements (selector discovery)

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden. It discloses the read-only nature, that it does not interact with the page, and that it loads the page through ScrapeUnblocker. It does not mention rate limits or how 'notable' elements are selected, but for a read-only discovery tool this is reasonable coverage.

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 core purpose and output, the second emphasizes read-only behavior, and the third gives the workflow context. All information earns its place and the most important details are 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?

Since there is no output schema, the description explains the return value (JSON list with selector, tag, text, attributes) sufficiently. It also connects the tool to the broader fetch_html workflow. Minor gaps such as empty results or blocked pages are not covered, but they are not essential for correct selection and 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%: url is described as 'The absolute URL whose elements you want to list' and proxy_country as 'Optional ISO country code to route through'. The tool description adds no extra parameter context, but with full schema coverage the baseline 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 states a specific verb and resource: loads a page and returns a JSON list of notable elements with ready-to-use selectors and attributes. It also distinguishes itself from the sibling fetch_html by positioning itself as the 'discovery half of interactive scraping' and explicitly noting it is read-only.

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 direct usage workflow: 'call list_elements to find the selectors you need, then pass matching steps to fetch_html'. It also clarifies that the tool does not interact with the page, implying that fetch_html is for interaction, which serves as an alternative and exclusion.

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