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

With no annotations, the description carries the full behavioral burden and handles it well: it discloses cost, that it fetches a URL, the exact checks performed, the return shape (score, individual checks, fixes), and the negative boundary (no model recommendation queries). It stops short of a 5 by omitting details like rate limits or failure behavior for invalid URLs.

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 earns its place: the first states cost and core function, the second lists the specific checks, the third describes output and the key limitation. The description is front-loaded and contains no filler.

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 input purpose, output content, and limitations well. The only gap is that it calls the paid alternative 'the paid audit' instead of naming request_visibility_audit directly, making sibling routing slightly less direct.

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 reinforces that the URL is the site to fetch and audit but adds no format or normalization details beyond what the schema already provides with its example.

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 is explicit: 'Fetches a URL and reports how readable it is to AI assistants and agents' plus a concrete list of checks (robots.txt permissions, text without JavaScript, JSON-LD types, llms.txt, sitemap.xml, A2A card). It also distinguishes itself from the paid audit by stating what it does NOT do, so an agent can tell it apart from request_visibility_audit.

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: free, immediate URL-level legibility audit, and explicitly says it does not measure actual model recommendations, which is the paid audit. However, it references 'the paid audit' rather than naming the sibling tool to use instead, so the alternative routing is implied rather than fully explicit.

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