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

Adds genuinely non-schema context: it does not fetch page bodies, it resolves sitemap location via robots.txt with a /sitemap.xml fallback, it is same-site scoped, and it has an explicit price point ($0.001). Missing is any statement about return shape/ordering beyond "URLs" and any rate/limit-per-call caveats, which keeps it off a 5.

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 sentences, front-loaded with the core action and source resolution, followed by the routing hint and cost. No filler, and the scoping ("same site only", "up to `limit`") is stated inline rather than buried.

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 does cover the essential nature of the return value (a URL list derived from sitemaps plus start-page links) and the cost model. What remains unstated is output ordering/dedup behavior and whether the caller can page beyond the limit, a minor gap for a read-only discovery tool.

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 the schema already documents url, limit, exclude_paths, and include_paths including the regex semantics and 1-5,000 bounds. The description only restates the limit cap and says nothing about the include/exclude regex filters, so it adds essentially no meaning beyond the schema.

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 ("List a website's URLs"), names the exact sources (robots.txt sitemaps, else /sitemap.xml, plus start-page links), and constrains scope ("same site only, up to `limit`"). It also explicitly situates itself relative to siblings contextfetch_extract_url and contextfetch_crawl.

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?

Explicitly says when to use it ("to find the right pages before contextfetch_extract_url or contextfetch_crawl"), naming the alternatives and the ordering condition that selects this tool. The "without fetching its pages" clause also implies the when-not (you want content, not discovery).

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