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

Annotations declare readOnlyHint=true and no destructive effects. The description explains the tool validates without contacting the target and returns a short-lived receipt. It also mentions the validation scope (quote, asset, price ceiling, etc.). This aligns with annotations and adds transparent behavioral details.

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 two sentences. The first sentence front-loads the main action and outcome. The second sentence provides critical parameter guidance. No redundant or filler content.

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?

The tool is complex (5 parameters, nested object, no output schema). The description explains the core functionality and key parameter behavior but omits details about the output format (receipt structure), error conditions, and payment confirmation. With no output schema, more context on the return value would improve completeness.

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 60% (some parameters have descriptions). The description adds unique value by explaining the effect of including 'allowed_payees' (safe_to_proceed vs. needs_review) and the requirement to forward the exact base64 header. This goes beyond the schema's static descriptions.

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 clearly states the tool performs a paid assessment by validating an x402 quote and returning a receipt. It specifies the exact operation: forwarding the PAYMENT-REQUIRED header, validating against policy, and returning a bound receipt. The purpose is distinct from siblings like 'intentfence_x402_readiness', which likely checks readiness before payment.

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 gives explicit guidance on the 'allowed_payees' parameter: supplying it yields 'safe_to_proceed', omission yields 'needs_review'. This tells the agent when to include it. However, it does not provide when to use this tool versus siblings or list alternative tools.

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