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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely new behavioral context beyond annotations: the 1-credit cost and the fact that a failed call is free, which matters for call planning. It stops short of describing return shape or pagination behavior.

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?

Two dense sentences with zero filler. The core action and its scope are front-loaded, and the cost caveat is appended compactly.

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 carries the burden of stating what comes back ('the page addresses it lists') and discloses cost, which is the main decision-relevant fact. It could say more about ordering or truncation behavior when limit is hit, but nothing essential to calling 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%, so all four parameters (including the idempotency key's 24-hour retry semantics) are already fully documented in the schema. The description restates limit's default of 100 and the filter behavior in plain language but adds no syntax or 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?

States a specific verb and resource: reads a site's sitemap.xml or sitemap index and returns the page addresses listed. The resource is specific enough to separate it from generic siblings like scrape or search, but it never explicitly names which sibling to prefer for non-sitemap page discovery.

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?

The usage context is implied rather than stated: it is clearly for sitemap.xml/sitemap-index inputs, and the credit-cost note ('costs 1 credit; a failed call costs nothing') helps an agent weigh the call. However, there is no explicit when-to-use/when-not guidance or named alternative (e.g. scrape for pages not in a sitemap).

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