x402 Price Quote (no payment)

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

The annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, which cover the safety profile. The description adds behavioral context beyond that: it specifically explains the mechanism (reads the HTTP 402 response) and what fields are returned. This is useful and consistent with the annotations, with no contradiction.

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 well-structured and concise: a single purpose sentence, one usage sentence, then clear Args and Returns sections. Every sentence earns its place, and the formatting is clean and scannable.

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 two-parameter tool, the description is fully complete. It explains what the tool does, when to use it, the parameters, and the return shape. The strong annotations cover safety, so no additional behavioral disclosure is needed.

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%: both 'url' and 'method' parameters already have meaningful schema descriptions (URL of the resource, HTTP method with enum/default). The description's Args section essentially repeats this information without adding new semantics. Baseline 3 is appropriate because the schema does the heavy lifting.

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+resource: 'Inspect an x402-paywalled URL WITHOUT paying' and clearly states it returns price, payTo address, and payment requirements from the HTTP 402 response. This distinguishes it from the sibling ordnet_x402_fetch, which likely fetches content after 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 provides clear context: 'Use this to check costs before committing.' It implies using this before actually paying/fetching, and notes it's free and read-only. However, it doesn't explicitly name alternatives (like ordnet_x402_fetch) or state when not to use this tool, so it falls just short of a 5.

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