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

With no annotations, the description carries the full burden of behavioral disclosure. It states it fetches and returns group counts but gives no information about side effects, access requirements, or what happens when the nine parameters are supplied. The description also contradicts the schema by implying a single purpose (robots.txt) while the schema allows many unrelated inputs, which is a transparency gap.

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, which is appropriately concise and front-loaded with the key purpose. It avoids unnecessary filler, though it could benefit from a few more words to clarify parameter usage without becoming verbose.

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?

The tool has nine parameters, none required, and no output schema. The description is too minimal to explain how these parameters relate to the core action. It doesn't clarify which parameters are used for the robots.txt fetch (e.g., is 'url' the target?), nor does it explain what 'group counts' means or how results are structured. For such a complex tool, the description is incomplete and would leave an agent guessing about correct usage.

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 each parameter is individually documented (e.g., 'discarded after the shape check', 'no disk access'). The description itself adds no parameter-specific meaning, but the schema already provides adequate semantics. Given the high coverage, a baseline of 3 is appropriate; the description neither improves nor detracts from the schema.

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 clearly states the core action: 'Fetch a public robots.txt and return group counts only.' This is a specific verb and resource, so an agent knows the primary function. However, it does not differentiate from siblings like fetch-status or web-fetch, which also fetch URLs, and it doesn't mention that the tool accepts many unrelated parameters, which could confuse an agent about what it actually does.

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. It doesn't mention any conditions, exclusions, or related tools. The description is purely declarative, so an agent has no information about when this is the right choice over fetch-status, web-fetch, or domain-shape.

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