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

Annotations only cover the safety profile (readOnly, idempotent, openWorld); the description adds substantial operational detail the annotations cannot: sampling of up to 40 addresses, HEAD requests at low concurrency, robots.txt exclusion for Agent Tools, a hard cap of 46 requests, host-only scope, and sitemap-index ordering. It also makes the key limitation explicit ('It is a sample, not every page').

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?

Front-loaded with purpose, then usage, then mechanism, then exclusions — a sensible order. It is dense and long, but nearly every clause (request cap, HEAD, concurrency, robots.txt) carries decision-relevant information rather than filler.

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, yet the description still summarizes the return shape (counts by status; per-address status and final address for broken/unreachable/redirected), and it pre-empts the main failure mode by stating the result is a sample with a bounded request budget. Nothing needed to invoke it 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% and the single 'domain' parameter is fully documented there, including the host-reduction behavior. The description's 'Pass the domain' adds no syntax or format detail 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?

Opens with a specific verb+resource+scope: 'Finds broken or redirected pages in a sitemap sample.' That is clearly distinct from siblings like trace_redirects (single redirect chain) and landing_page_check (one page), so an agent can route 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?

Gives concrete triggering user phrasings ('are any pages of shop.example.com broken?', 'check my sitemap for 404s') and explicit exclusions: 'Do not use it for private or local addresses, to read page content, or to monitor a site over time.' When-to-use and when-not are both stated.

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