Verify a signed observation receipt (free)

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

No annotations are provided, so the description carries the burden. It explains the receipt's cryptographic nature (Ed25519 attestation) and the verification action, implying read-only behavior. It does not discuss error handling or side effects, but for a stateless verification, this is adequate; the 'free' in the title hints at no cost.

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 sentences provide background and action without fluff. The first sentence defines the receipt, the second explains the verification and use case. No wasted words.

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 verification tool with no output schema, the description covers the purpose, the input structure, and the intended scenario. It does not explicitly state return values or error behavior, but the verification context makes those predictable. A 4 reflects the small gap.

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?

The schema only describes 'receipt' as 'the receipt object from an event', but the description specifies the expected fields {alg, keyId, statement, sig}, adding meaningful structure. With 100% schema coverage, baseline is 3, but the added field detail elevates it to 4.

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 explicitly states the tool 'checks' a receipt 'against the service key', clearly identifying it as a signature verification tool. The title 'Verify a signed observation receipt' reinforces the verb and resource, and the receipt structure is defined, distinguishing it from the coordination/health sibling tools.

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?

The description explains when to use it: to validate evidence from another agent without trusting that agent. It does not name alternative tools, but the context is clear and no sibling offers the same verification capability, so it earns a 4 rather than a 5.

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