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

Beyond the annotations, the description discloses the full verdict contract, the paid nature ($0.50), the required payment sequence (generate the operation id per purchase, preserve it across retries, add _x402_payment_signature after satisfying the challenge), and precisely how a stable _salt19_operation_id delivers at-most-once semantics. This meaningfully enriches the idempotentHint=true annotation rather than restating it.

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 sentences with zero waste. The first sentence front-loads the core mapping/verdict behavior, and the second and third cover the mandatory payment and idempotency contract. Every sentence carries information an agent needs before invoking the tool.

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 paid 7-parameter tool with a payment challenge and retry semantics, the description covers the essential operational surface: core behavior, returned verdicts, pricing, payment sequencing, and idempotency guarantees. The output schema handles return values and the input schema (100% coverage) documents parameters, leaving little the description must add. It slightly undersells the evidence object's relation field, but that is covered by the schema.

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 100%, so the baseline of 3 applies — the schema already documents every parameter. The description does add workflow sequencing for _salt19_operation_id and _x402_payment_signature (generate once, preserve across retries, add after the challenge), which is useful but modest; it complements rather than substantially extends the schema.

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 opens with a specific verb and resource: 'Map an autonomous agent claim or output to supplied evidence' and names the exact verdict enum returned (SUPPORTED, PARTIALLY_SUPPORTED, NOT_PROVEN, CONTRADICTED) plus the explicit output elements (unsupported elements, contradictions, missing evidence, recommended verification). This distinguishes it from sibling verifiers like agent-plan-verifier and verify-decision-receipt without needing their 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?

The description provides clear operational context — it is a paid verification service ($0.50 via x402) with a two-phase payment flow and at-most-once retry semantics — but it never states when to prefer this tool over sibling verifiers or any exclusions. The 'when' is implied by the stated purpose rather than made explicit.

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