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

Adds substantial context beyond annotations: sitemap-first strategy, same-host link discovery, max 50 URLs, no page content, robots.txt compliance, full return shape, caching, and detailed metering (100 calls/day shared bucket, 1 credit over x402, no API key, 402 accepts[]). Annotations already cover safety, but the description provides the operational behavior an agent needs.

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-loads purpose, then usage, then return shape, then metering. Every sentence carries actionable information; the metering detail is dense but necessary for a paid tool. No filler.

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?

Given no output schema, the description explicitly describes the return object fields including urls with source tags, cached, took_ms, and metering. It covers safety boundaries, scope, and cost — everything an agent needs to call correctly.

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%, so both parameters are fully documented in the schema. The description repeats the 50-URL limit and URL source behavior, which is marginally useful, but adds no syntax or format detail beyond the schema. 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?

States a specific verb and resource (discover URLs of one site) and explicitly distinguishes itself from crawler siblings, naming the exact boundary (max 50, no page content). An agent can identify this tool's job without opening the 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?

Provides explicit 'when to use' and 'do not use' sections, naming the alternative pattern (web_crawl) and the robots.txt constraint. It tells the agent both the positive trigger (needing a page list before fetching) and the anti-pattern.

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