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

Annotations already declare readOnlyHint and openWorldHint, and the description adds genuinely new behavior: the pricing model ($0.005 USDC per call, x402 or credits) and that sitemap indexes/robots.txt are followed. It stops short of noting failure cases, crawl politeness, or result shape.

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 tight sentences; the core purpose and scope are front-loaded, and the cost detail is a compact parenthetical. No filler or repetition of the title.

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 simple two-parameter read tool with full schema coverage and annotations, the description covers purpose, scope, and cost. With no output schema, a brief note on what the returned URL list looks like would have closed the remaining gap.

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 both parameters (url, limit) are already documented in the schema. The description adds nothing about parameter syntax or semantics beyond that, which makes the baseline 3 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?

States a specific verb (list) and resource (a site's URLs from its sitemaps), plus the resolution behavior (follows robots.txt and sitemap indexes). This is enough to distinguish it from siblings like tools_feed or extract_page 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?

Usage is implied by the purpose — use it to enumerate a site's URLs — but there is no explicit when-to-use, when-not, or alternative (e.g., tools_feed for RSS/Atom discovery). The robots.txt note gives context but not selection guidance.

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