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

Annotations already declare readOnly/openWorld/idempotent/non-destructive, and the description goes further with a concrete 5 MB read cap and a non-obvious semantic: an index is validated as an index and its children are listed but not fetched. Those details materially shape what the agent can expect and are not derivable from the annotations.

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 sentences, front-loaded with the discovery-then-validate action, followed by the operating constraints. No filler or restatement of the title.

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 no output schema, the description says what is checked (protocol plus Google rules) but not the shape of the result — error list, pass/fail, child sitemap entries — so the agent must infer the return format. Everything needed to call it correctly is present, which is the more important half.

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 both parameters are already documented with examples and the standard-ports restriction. The description only reinforces the auto-discovery behavior of omitting sitemap_url; it adds little syntax or meaning beyond the schema, so the 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?

Names a specific action chain — locate a site's XML sitemap via robots.txt or conventional paths, then validate it against sitemaps.org and Google rules. The resource (XML sitemap) and scope (validation, not generation or submission) are unambiguous and distinguish it from siblings like robots_txt_test.

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?

Clear that the tool is for validating a sitemap and that auto-discovery happens when sitemap_url is omitted, which tells the agent how to invoke it in both modes. It stops short of stating when to prefer a sibling (e.g., robots_txt_test for robots.txt itself) or what happens when no sitemap exists, so no explicit exclusions.

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