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

Annotations are entirely absent, so the description must carry the full behavioral burden. The phrase 'return group counts only' is a useful behavioral disclosure—it tells the agent not to expect the full robots.txt content but just a summary. However, the description does not cover expected failure modes (e.g., unreachable host, malformed robots.txt, redirect handling), rate limits, or whether the tool modifies any state. The 'discarded after the check' note in the json parameter adds some transparency, but it is incidental.

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 extremely concise—a single sentence with no filler. It front-loads the main action (fetch) and the key constraint (group counts only). While it could be slightly expanded to cover usage context, it earns a high score for efficiency and directness. Every word in the sentence contributes to the core message.

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 tool with 4 parameters, zero annotations, and no output schema, the description is too sparse. It does not clarify the role of unrelated-looking parameters (json, zone, host vs url), nor does it explain what 'group counts' means (e.g., does it count user-agent groups, disallow rules, allow rules?). The lack of an output schema increases the need for the description to state return semantics, but it only says 'group counts only,' which is insufficient for an agent to confidently infer the exact output shape.

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%, meaning every parameter already has a description in the schema. The tool description itself adds no parameter-level meaning beyond the schema. The parameters—url, host, json, zone—are a disparate set and the description doesn't clarify how they relate to fetching robots.txt. For instance, why is a 'zone' or 'json' parameter relevant to a robots.txt fetch? The schema descriptions are present but shallow, and the tool description does not compensate for the apparent mismatch between parameters and the tool's stated purpose.

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 clear verb and resource: 'Fetch a public robots.txt and return group counts only.' This names the tool's main action, but it does not differentiate it from the sibling tools in any way. Since no sibling descriptions are provided, it is difficult to determine what distinguishes inspect-robots from a generic fetch or validation tool, so the purpose is clear but not fully contextualized.

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 no guidance on when to use this tool versus alternatives. It does not mention any exclusions, prerequisites (e.g., valid HTTPS URL, public accessibility), or scenarios where a different tool would be more appropriate. The only hint is the word 'public,' which implies it is not for private or authenticated resources, but this is not explicit enough for confident decision-making.

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