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

Annotations already establish readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds real value beyond that: the fetch source (https://<domain>/robots.txt), wildcard rule inclusion, and the crucial caveat that server-side blocking is NOT reflected — an interpretation limit annotations cannot express.

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?

Two dense sentences: the first states what is fetched and reported, the second immediately qualifies the scope. Nothing is wasted and the most important constraint is front-loaded in a compact package.

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?

With no output schema, the description carries the burden of describing results, and it does so by naming the crawler set and allowed/blocked status plus wildcard handling. Slightly thin on response shape (e.g. per-crawler structure), but sufficient for an agent to call and interpret it.

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?

Single parameter with 100% schema description coverage; the schema already documents the domain format and fetch URL. The description adds no syntax or validation detail beyond what the schema provides, so baseline 3 applies.

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?

States a specific verb (fetches robots.txt) and resource (a domain's AI crawler rules), and enumerates exactly what it reports — GPTBot, ClaudeBot, PerplexityBot, Google-Extended, CCBot and wildcard rules. An agent can distinguish this from generic siblings like dns_lookup or security_headers without opening either schema.

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 boundary statement 'Reflects robots.txt only, not server-side blocking' usefully scopes when the result is trustworthy, but no alternatives are named and no when-to-use trigger is given. Usage is implied by the narrow scope rather than stated.

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