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

Annotations already declare readOnly, idempotent, non-destructive behavior; the description adds substantive context beyond them: no Groth16 re-verification, possible receipt provenance checks, unreconstructable missing payloads, and the payment settlement/authorization flow. No annotation contradiction is present.

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?

The retrieval purpose is front-loaded, and the later sentences cover genuinely relevant lookup and payment behavior. It is dense and longer than typical, but the detail is mostly purposeful for a paid retrieval endpoint.

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 an output schema, rich annotations, and 100% parameter description coverage, the description fills the remaining behavioral gaps: identifier selection, missing-record behavior, verification limits, and L402 authorization handling. It is complete enough for an agent to invoke correctly.

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 already 100%, so the schema documents accepted hash formats and jobId UUID use. The description reinforces the exactly-one-of rule and maps identifiers to lookup behavior, adding some useful semantic context without introducing new argument syntax.

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: retrieve one retained proof payload, signed receipt, or lifecycle-only status by exactly one identifier. It names the accepted identifier families and explicitly contrasts with proof.list and proof.verify, so an agent can distinguish it from siblings.

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?

Explicitly says to use exactly one of hash or jobId, names proof.list for discovery and proof.verify for cryptographic verification, and explains the 404-before-payment behavior. It also gives the L402 payment/retry procedure, leaving little to inference.

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