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

Goes well beyond the annotations: reveals latency (4-9s), x402 paid-per-call billing, a 60 calls/min per-client rate limit, that failed/timed-out/capacity calls are not charged, and that calls are independent and parallelizable. Annotations only cover the read-only/open-world profile, so this fills the real behavioral gap.

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 output shape, then routing, then usage and billing. Efficient overall, though the 'one question per call' instruction is stated twice (once in usage, again in the closing parallel-calls sentence), which is slightly redundant.

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 an output schema present and rich annotations, the description supplies everything else an agent needs: latency expectations, cost model, rate limits, failure billing behavior, and invocation constraints. Nothing material is missing for a single-parameter 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 coverage is 100% so baseline is 3, but the description adds meaningful semantics the schema lacks: name the people, places and dates the question depends on, and ask exactly one question per call. This is genuine invocation guidance beyond the 1-500 character constraint.

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+resource (answers a research question from the live web) plus concrete output shape (max 80 words, up to 3 source URLs, {answer, sources}) and latency. It explicitly disambiguates from web.search and research.factcheck, so an agent can select it without opening other schemas.

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?

Gives explicit routing: 'use web.search for raw links or research.factcheck to verify a claim', and states the calling convention 'one question per call' with the reason (multiple questions get one blended answer). When-to-use and the alternatives are both named.

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