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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds real value beyond that: it discloses the concrete checks performed and the cost/behavior profile ("A handful of fetches, no AI"), telling the agent this performs bounded network I/O rather than an LLM-backed analysis.

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?

Three short sentences, front-loaded with the use trigger, followed by the checks reported and a cost note. No filler, no repetition of the title or name, and the most decision-relevant information comes first.

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 appropriately enumerates what the result will cover, which is enough for an agent to interpret the response. It stops short of describing the result's shape (per-check booleans vs. prose findings), a minor gap for an otherwise simple, single-parameter read-only tool.

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?

There is a single parameter with 100% schema description coverage, and the schema already explains that a bare domain like example.com is acceptable. The description adds nothing beyond that (e.g., scheme handling, redirects, subdomain behavior), so the baseline of 3 applies when the schema carries the burden.

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 (check) and resource (XML sitemap) and enumerates exactly what is verified: reachability, parseability, robots.txt declaration, and absence of cross-host entries. This lets an agent distinguish it from the adjacent crawler tools (check_ai_crawler_access, check_ai_readiness) without opening any 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?

"Use this when someone wants their XML sitemap checked" gives a trigger but is essentially a restatement of the purpose rather than routing guidance. With overlapping siblings like check_ai_crawler_access in the same family, the description never says when to prefer this tool over those or what it excludes, leaving usage to inference.

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