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

Annotations already establish readOnly/idempotent/non-destructive. The description adds value beyond them by disclosing that it is free (cost), that it recomputes a hash and recovers the signer (the mechanism), and that it reports authenticity and integrity. It stops short of describing failure behavior for tampered or missing 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?

Two tight sentences with the cheap-cost signal front-loaded, then the core action and outcome. No filler and nothing buried.

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?

An output schema exists so return values needn't be explained, and the safety profile is covered by annotations. The description is complete enough for a one-param verification tool; only the failure/negative-result behavior is left implicit.

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?

With a single parameter at 100% schema coverage, the schema already documents 'document' and its attestation requirement. The description's 'any signed Settled response (attestation included)' restates the schema rather than adding new syntax, so the 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?

The description gives a specific verb+resource ('Verify a signed Settled response') and then states exactly what happens: recompute the hash, recover the signer, and report authenticity/integrity. This is distinct from siblings like settled_check or settled_preflight, so an agent can route correctly without reading schemas.

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 clearly states the input condition to invoke it ('pass any signed Settled response') and adds a cost signal ('Free'), giving clear context for use. It does not name alternatives or an explicit when-not, so it falls short of the 5 reserved for definitions that route between siblings.

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