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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description adds important behavioral detail beyond that: it will 'never pays or signs anything' and it lists the exact categories of evidence used to form a verdict. This goes beyond the structured annotations and is especially useful in a payment-safety context.

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?

The description is front-loaded with the core question and verdict output, then lists the evidence sources in a compact colon-delimited structure. Despite its length, every clause describes a relevant check or safety property, and there is no redundant 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?

For a complex, read-only verification tool with no output schema, the description explains the return shape (verdict plus reasons) and enumerates the evidence sources. Combined with full schema coverage and clear annotations, an agent has enough information to select and invoke it 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 description coverage is 100%, so both parameters are already documented in the schema. The description restates that the target can be an endpoint URL, seller domain, or wallet address, but it does not add parameter-level semantics beyond what the schema provides; the baseline of 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?

The description states a specific decision task ('Should your agent pay this?') and a specific resource class (x402 / pay-per-call endpoint, seller, or wallet address). It also names the return verdicts and the checks performed, so an agent can distinguish it from sibling tools like vendor_trust_profile or x402_market_report 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?

It gives a clear trigger: 'Run before paying an x402 / pay-per-call endpoint, an unfamiliar seller or a wallet address.' That is strong contextual guidance, but it does not state when not to use the tool or name an alternative sibling for overlapping trust/readiness checks.

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