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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is largely covered. The description adds useful behavioral context beyond that: the tool is free, returns a three-way decision with reasons and report evidence, and require_audit_receipt triggers only an optional settlement-backed receipt handoff rather than submitting payment.

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 description is a single tight sentence that front-loads the core decision and follows with the optional receipt handoff. Every clause earns its place, with no redundant restatement of the name or annotations.

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?

Given that annotations cover safety semantics, all four parameters are fully described in the schema, and an output schema exists, the description is nearly complete for an agent to call the tool correctly. It could be slightly stronger with an explicit pointer to when an agent should choose this over sibling readiness or verification tools, but the core decision context is present.

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 100%, so the schema already documents every parameter, including endpoint safety, max_usdc ceiling semantics, agent_policy defaults, and require_audit_receipt behavior. The description reiterates the policy modes and receipt handoff but adds no new parameter-level semantics beyond what the schema provides, so the baseline of 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 states a specific verb and outcome: a free pre-payment policy decision returning allow, review, or deny for one x402 endpoint. It is clear what the tool does, though it does not explicitly differentiate itself from sibling verification tools such as x402_readiness_verify or agent_trust_preview.

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 phrase 'Free pre-payment policy decision' implies this belongs before a payment is attempted, and the description notes that require_audit_receipt adds an optional post-allow handoff. However, it gives no explicit when-not guidance and does not name an alternative tool for related checks, leaving the agent to infer routing.

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