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

With no annotations, the description carries the full burden and does: cost (0.05 USDC on Base), payment protocol via x402, the exact error contract (isError result with a 402 object in structuredContent), the _meta['x402/payment'] retry key, signing/logging of the result, and a free sample endpoint. This is precisely the behavioral context an agent cannot get from schema.

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-loaded with the value proposition, then cost, then the call protocol; no filler sentences. It is dense — several clauses about payment mechanics are packed into one paragraph — but each clause is operationally necessary.

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?

No output schema exists, and the description still conveys the shape of the result: one signed, logged report with per-citation grades from a four-value taxonomy. Minor gaps remain, such as whether the report includes the fetched page text or partial-batch failure behavior.

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 0%, so the description must compensate, and it mostly does: it explains that the tool accepts up to 8 quote-and-link pairs, or that citations can be extracted from the answer text, which disambiguates the citations-vs-answer split. It does not spell out the expected keys inside each citation object (quote, url) or what an empty answer implies.

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 verb and resource (check citations in an answer) plus the output taxonomy — verbatim, paraphrase, stitched, not found — and a hard limit of 8 pairs. It is unmistakably distinct in substance from siblings like verify_quote, though it never names an alternative explicitly.

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 a clear trigger ('before an answer ships') and, unusually, a full invocation protocol: call without payment first to get the 402 requirements, then retry with the signed payment. It stops short of contrasting this with verify_quote or paid_proof_of_publication, so selection among overlapping siblings is left to inference.

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