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

The annotations already establish read-only, open-world, non-idempotent behavior, but the description adds important operational detail: 512 KiB/1000-entry bounds, warnings on large sitemaps, invalid XML/execution errors not charged, empty matches charged, pricing, free quota, and that repeats are not free. This goes well beyond the structured annotations without contradicting them.

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 front-loaded with the core behavior, limits, and usage guidance, and it remains dense rather than padded. There is slight redundancy around charging and repeat calls, but most sentences earn their place by covering billing, limits, or scope.

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?

An output schema exists, so return-value details need not be repeated, and the annotations plus full schema coverage handle safety and parameters. The description supplies the remaining operational context an agent needs: bounds, non-crawling behavior, error/charging rules, and the intended relationship to /extract.

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 schema already fully documents url, offset, maxUrls, and contains. The description mentions filtering and pagination at a high level but does not add parameter-specific meaning beyond what the schema provides.

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 states a specific verb and resource: it reads one public XML sitemap or sitemap index and returns structured URLs and source-reported dates. It also distinguishes its scope from crawling/extraction by noting gzip support, filtering, pagination, and that it does not follow child sitemaps.

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?

It explicitly says to use this tool to find which pages of a docs site to read before calling /extract, giving a concrete upstream role relative to a sibling tool. It also states exclusions: does not crawl pages or follow child sitemaps.

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