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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so safety is covered. The description adds genuinely new context: the call is free (no cost concern) and verification uses the *current* public key, implying receipts signed under a rotated key may fail. It omits what happens on an invalid signature (error vs. a payload flag), which keeps it from a 5.

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?

One sentence plus a cost marker, with the verb and resource front-loaded and no filler. 'Free.' is terse but conveys genuinely useful pricing information rather than padding.

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 single-parameter, read-only verification tool with no output schema, the description covers input format, the verification basis, cost, and return value. The only real gap is failure semantics for an invalid or expired receipt.

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 0% and the sole parameter is undocumented in the schema, so the description carries the burden. Describing the receipt as a 'compact JWS' tells the agent the expected format (a serialized JWS string, not a JSON object), which is meaningful beyond the bare 'string' type.

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 names a specific verb ('Verify') and resource ('Approval Relay decision receipt (compact JWS)'), plus what comes back ('decoded payload'). It does not explicitly contrast itself with get_approval or request_approval, but the purpose is unambiguous on its own.

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?

There is no explicit statement of when to use this versus get_approval or request_approval, and no prerequisites or exclusions. The phrase 'against the current public key' hints at post-issuance verification, but the agent must infer that context entirely.

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