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 does communicate that only group counts are returned, not the full robots.txt, which is useful. However, it does not mention behavior on missing/blocked robots.txt, error responses, or the meaning of 'groups', leaving important behavior implicit.

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 one short, front-loaded sentence with no filler. It conveys the core action and the limited return value efficiently.

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 four optional parameters, no output schema, no annotations, and a disconnected input schema, the description is too thin. It does not clarify the expected input for fetching a robots.txt, leaving an agent with ambiguous parameter choices and incomplete expectations about behavior.

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?

Although schema descriptions cover 100% of parameters, they are generic and poorly tied to this tool: 'url' is described as 'HTTPS URL to normalize or cite', and 'json' and 'zone' are unrelated to fetching robots.txt. The description does not explain which parameter to use or how the parameters relate to the robots.txt fetch.

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 an explicit action ('Fetch'), a concrete resource ('a public robots.txt'), and a precise output shape ('return group counts only'). It clearly distinguishes this tool from its siblings by naming the robots.txt inspection focus.

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?

There is no guidance on when to use this tool versus alternatives like domain-shape, normalize-url, or validate-json. The description gives no context, prerequisites, or exclusions to help an agent decide between tools.

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