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

With readOnlyHint=true annotation, the description adds valuable context that this tool mirrors constants and the live PAYMENT-REQUIRED header remains authoritative. This clarifies the tool's non-authoritative nature and its behavioral scope beyond the annotation, providing useful context for the agent.

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 with no redundancy. The first sentence states the tool's function and output fields; the second clarifies authority. Front-loaded with essential information, making it efficient for quick comprehension.

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 simple read-only tool with one parameter and no output schema, the description adequately covers what the tool returns (fields) and its relationship to the authoritative header. No critical information is missing for the agent to call it 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 100%, with detailed examples for the product parameter. The description adds no new meaning beyond stating it applies to 'one payable URL or product path', which is already implied by the schema. Baseline 3 is appropriate when schema fully documents parameters.

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 gets exact x402 payment terms for a payable URL/product path, listing specific fields (price, asset, network, payTo, scheme). This distinguishes it from siblings like check_10q_coverage, how_to_pay_x402, and list_research by focusing on retrieving payment term constants.

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 does not provide explicit guidance on when to use this tool versus siblings. It mentions the live 402 response is authoritative but does not state when to choose this tool over how_to_pay_x402 or check_10q_coverage. No alternatives are named, leaving the agent to infer usage context.

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