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

With no annotations, the description must carry the full burden. It discloses that the tool is read-only and returns only counts, but it omits error handling, URL requirements, or what happens if the robots.txt is missing. The mismatch between the description and the schema parameters also introduces confusion.

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 a single sentence, front-loaded with the action, and contains no filler. It is appropriately concise, though it may be too terse given the schema mismatch.

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 schema's four parameters and the lack of an output schema, the description is incomplete. An agent cannot confidently determine which parameters to provide (e.g., does it need url or host?) or what 'group counts' means. The mismatch between the stated purpose and the schema leaves significant gaps.

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 schema provides descriptions for all four parameters, but they are mismatched with the tool's purpose (e.g., 'JSON text to validate' and 'IANA timezone name' have no relation to robots.txt). The tool description does not clarify which parameters are actually used or how they relate, so it fails to compensate for the schema's generic and misleading descriptions.

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 action: fetch a public robots.txt and return group counts. It is clear and uses a verb+resource, but it does not differentiate from sibling tools like normalize-url or validate-json, which could be relevant in the same inspection suite.

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?

No guidance is provided on when to use this tool versus alternatives. There is no mention of prerequisites, exclusions, or context that would help an agent decide between this and sibling tools.

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