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

Annotations already declare readOnlyHint and openWorldHint, so the description's added value is the operational detail it supplies: a hard cap of 10 results, an explicit return shape, per-call credit pricing, and the fact that schema-invalid input is rejected before billing. That last point is genuinely useful pre-call information. It stops short of explaining ranking/scoring behavior or any rate limiting.

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 compact sentences, front-loaded with what the tool does, then result shape, then cost. Every sentence carries information an agent needs. It is dense but not padded.

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 read-only, open-world lookup with no output schema, the description covers the return shape, result cap, and cost model, which is most of what an agent needs before calling. The remaining gap is the absence of any sibling disambiguation, which matters given how many adjacent tools exist here.

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%, including the URL safety restrictions and the 1-10 bounds on numResults, so the schema carries the parameter burden. The description only restates the 'up to 10 results' ceiling and the public-URL requirement, adding little beyond structured data. Baseline 3 applies.

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 concrete operation and resource: pages similar in meaning to a given public URL, with highlights. It is specific enough to act on immediately. It does not, however, distinguish itself from the sibling 'similarity' or 'web-search' tools, so the agent must infer which one to pick.

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 input constraint (a public URL) and the exclusion of private/internal addresses, but there is no explicit when-to-use guidance or comparison against alternatives such as 'similarity' (pairwise text comparison) or 'web-search'. The agent must infer the boundary itself.

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