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

Goes well beyond the annotations: discloses the sampling strategy (evenly across the file, up to 5 children of a sitemap index), the user agent used, that Googlebot-specific robots.txt blocking is checked, the canonicalization check, and the identical/future-dated lastmod reporting. It also discloses the separate rate-limit budget and expected duration, which are exactly the cost signals an agent needs before calling.

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 the core action and the input alternatives, then the sampling mechanics, then cost/rate limits. It is dense but nearly every clause carries operational meaning; the closing URL reference to the web tool is the one mildly expendable element.

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?

For a single-parameter read-only audit with no output schema, the description supplies everything the agent needs: valid inputs, what is examined, what findings are produced, how long it takes, and how it is rate-limited. No material gap remains.

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 coverage is 100% and the schema already explains that a hostname is accepted with https assumed. The description adds value on top by explaining the consequence of passing a hostname — the robots.txt-declared sitemap is resolved — which tells the agent what actually gets audited in each case.

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 and resource ('Audit a sitemap') and immediately defines scope: sampling up to 200 URLs, fetching with stillindexedbot, and the exact problem classes it flags. This is far more than a restatement of the name and lets an agent distinguish it from stillindexed_check_sitemap, which presumably only parses/validates rather than samples and fetches.

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?

Explains the two accepted input modes (sitemap URL vs hostname, with robots.txt resolution) and gives operational context (90s runtime, 2 audits/IP/hour under a separate allowance). It stops short of naming when to prefer this over stillindexed_check_sitemap or stillindexed_bulk_check, so alternative-selection guidance is implied rather than explicit.

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