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

Beyond the readOnly/openWorld annotations, it discloses auth context (free, no account), statelessness (holds no database), and the key behavioral edge case that attestations from other issuers return a clear 'no'. This is exactly the extra context annotations cannot carry.

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 and organized with When to use / Parameters / Returns sections. Slightly padded by promotional phrasing ('Free, forever, no account', 'which is the point'), but every structural element earns its place.

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 compensates by summarizing the return values (signature validity, issuer match, reasons). For a single-parameter verification tool, nothing needed to invoke it correctly 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?

Schema coverage is 100% and the description's parameter note restates the schema text almost verbatim (full attest_page response or just its attestation object). Baseline 3 is appropriate since the schema does the work with no added meaning.

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 and resource: hand in an attestation and learn whether the signature is valid and whether this service issued it. It also implicitly separates itself from the sibling attest_page by naming it as the producer of the artifact being checked.

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?

Explicit 'When to use' line gives two concrete triggers: someone handed you an attestation, or you want to check one of your own. No when-not guidance or named alternative tool, but the use case is unambiguous.

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