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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds real behavioral context beyond that: the data is read live from the blog's custom domain, and only the first 25 URLs are surfaced even when more are counted. It stops short of noting failure modes (e.g., missing/unreachable sitemap), which keeps it from a 5.

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 sentences with zero filler, front-loaded with the usage trigger, followed by return shape and the disambiguation. Every sentence earns its place.

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 an output schema present the description needn't enumerate return values, yet it still flags the count/first-25 distinction that could surprise an agent. Combined with rich annotations and a fully documented schema, nothing needed to call this tool correctly is missing.

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 blogId, locale and maxUrls are already documented with formats and bounds. The description restates the 25-URL listing cap but adds no meaning beyond the schema, which is the expected baseline when the schema does the heavy lifting.

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?

Specific verb+resource (read a blog's sitemap URLs) plus the concrete return shape: URL count and the first 25 URLs with language and last-modified date. It explicitly distinguishes itself from the sibling set with 'Not for the posts stored in Polyblog,' so an agent can rule out search_articles/get_article.

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?

Gives an explicit trigger ('when someone asks what pages their blog's sitemap lists, or which pages are available to link to') and an explicit exclusion ('Not for the posts stored in Polyblog'). Nothing about selection is left to inference.

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