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

With zero annotations, the description carries the full burden and does so well: it discloses the resolution strategy (checks robots.txt, then /sitemap.xml), handles sitemap indexes and .xml.gz variants, and returns last-modified dates. It also discloses the payment requirement and exact price ($0.002 USDC via x402), which is critical pre-invocation context. It stops short of failure modes or whether a missing sitemap returns an error or an empty list.

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 short sentences, all load-bearing: what it returns, how to invoke it plus the resolution behavior, and the cost. The purpose is front-loaded before the mechanics, and nothing is repeated from the schema.

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 no output schema, the description correctly states the return shape (page URLs with last-modified dates), and it covers the non-obvious cost model. The one gap is outcome disclosure: whether a site lacking a sitemap produces an error, an empty result, or a robots.txt-derived fallback is left unstated.

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%; both url and limit are fully documented in the schema, including the 1-5000 bound on limit. The description's note that url accepts 'any page on the site' only slightly extends the schema's 'Any page on the site, or the sitemap URL itself', and the limit parameter is never mentioned. Baseline 3 is appropriate.

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 opening clause pairs a specific verb ('List') with a specific resource ('a website's page URLs ... from its sitemap'), so the function is unambiguous. It never names a sibling tool such as page_links or read_page, but the resource boundary between sitemap discovery and reading page content is obvious enough for an agent to choose correctly.

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?

'Give it any page on the site' tells the agent what to feed the url parameter, which is near-usage guidance rather than actual usage guidance. There is no explicit statement of when to prefer this over page_links or read_page, no mention of when it will fail (site with no sitemap), and no exclusions, so the routing signal is only implied.

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