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

Annotations already establish the safe read-only, idempotent, non-destructive profile, so the description's added value is the ad policy ('lookups carry no ads... offers come only with check_website results') and the ranked-match return shape. It discloses behavior beyond the structured safety hints, though return details partially overlap the existing output 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, front-loaded with the core action and examples before the return shape and ad policy. Every sentence carries information, though the trailing ad/offers sentence is dense and reads more like a sibling-routing note than core usage.

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 lookup with an output schema and full annotation coverage, the description supplies what is needed: input forms, ranking cap, and the shape of guidance returned. Minor gaps remain around no-match behavior and how it differs from get_error/list_errors.

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?

With a single parameter at 0% schema description coverage, the description compensates by enumerating accepted query forms: a browser error token, an HTTP status code, or pasted error text. That is meaningful semantic guidance beyond the bare string schema, though it says nothing about the 200-character limit or normalization behavior.

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 and resource set: 'look up a browser error, HTTP status code or pasted error text', with concrete examples (ERR_CONNECTION_REFUSED, 503). It does not explicitly differentiate itself from the sibling tools get_error and list_errors, so the agent must infer the distinction from the 'up to five ranked matches' phrasing.

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?

Clearly signals the input contexts it is meant for (browser errors, HTTP status codes, pasted error text) and implicitly routes website-checking to check_website by noting offers appear only there. No explicit when-not or statement of how it differs from get_error/list_errors, which would have made this a 5.

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