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

Annotations already declare readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds value beyond that by disclosing the return payload ('whether it is valid, the anonymous id, and how the challenge went') and the 'issued here' provenance constraint, though it says nothing about failure modes for unparseable attestations.

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?

Three short sentences with zero filler: purpose first, applicability second, return values last. Every sentence carries distinct information and nothing is repeated from the annotations or schema.

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 only two parameters, full schema coverage, annotations, and no output schema, the description does the job of describing the response shape. Only minor gaps remain, such as what happens when verification fails versus when the attestation is malformed.

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%: both 'audience' and 'attestation' are documented in-schema, including that attestation comes from enter. The description adds no parameter-level detail beyond that, so the baseline of 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?

Uses a specific verb ('Verify') on a specific resource ('an attestation') and scopes it with 'issued here', so an agent can tell it apart from enter/get_entry_challenge. It does not name a sibling explicitly to further sharpen the boundary, but the resource and scope are unambiguous.

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?

'For sites that received one from an agent' gives a clear condition for when this tool applies, which is the key gating context. It stops short of stating when not to use it or naming an alternative tool, so it is clear context without exclusions.

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