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

The description states the output is 'group counts only,' which is honest about the return scope. However, no annotations are provided, so the description carries the full burden of behavioral disclosure. There's no info about caching, redirects, errors, or what happens with unparseable robots.txt files.

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 minimal and efficient — one short sentence. It's front-loaded with the main action. No wasted words, though it's arguably too terse.

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 mismatch between required parameters (0) and the tool's stated purpose (fetching a robots.txt — which should require a URL), this tool has a significant gap. The description doesn't clarify which parameters are needed for this tool to work. No output schema exists, and the description doesn't note any return value details beyond 'group counts.'

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 JSON schema already documents all four parameters. The description doesn't add any parameter-level semantics beyond what's in the schema. The relevance of parameters like 'json' and 'zone' to fetching a robots.txt is unclear — only 'url' or 'host' seem naturally connected.

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 says 'Fetch a public robots.txt and return group counts only,' which gives a specific verb (fetch), a resource (robots.txt), and a return type (group counts). It's clear about the narrow scope but doesn't explicitly distinguish this from other tools that might fetch web resources, so no sibling differentiation.

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 doesn't explicitly state when to use this tool. The sibling-tools list is just a single entry 'citation' — the description doesn't mention it at all. The tool name 'inspect-robots' suggests robots.txt inspection, but the description provides no guidance on when this is preferred over alternatives.

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