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

Goes well beyond the readOnly/idempotent annotations: failure behavior is spelled out (valid is false, reason identifies forged signature or expiry, expired still returns the claims), auth is stated (public, no credential), and a deployment-specific 501 condition is disclosed with an offline fallback. These are exactly the traits an agent cannot get from structured fields.

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 core question and the input, then layers failure semantics, auth, and the 501 fallback — each sentence earns its place. The final sentence is compound (501 plus offline alternative), which costs a little readability but not enough to trim.

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 no output schema, the description takes on the return-value burden and does so: valid/reason fields, the expired-but-claims nuance, and the 501 signal. Nothing an agent needs to call this correctly or interpret a failure is missing.

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?

Only one parameter, and schema coverage is 100% with a description already present on jws. The description's 'Pass its jws string' and 'the signed quote you were given' add framing but no format or encoding detail beyond the schema, so 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 specific verb (check/verify) and a precise resource (a signed price quote received from a seller), and enumerates the three questions it answers: issuer, integrity, validity. This clearly distinguishes it from siblings such as verify_webhook_signature, verify_price, and verify_storefront_domain.

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 clear context for use (you received a signed quote from a seller) and names one explicit alternative — verifying offline against /.well-known/quote-keys.json. It doesn't compare itself to nearby siblings like verify_price or get_ucp_quote, so routing among verification tools is left partly to inference.

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