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

With annotations only covering readOnly and openWorld, the description adds substantial context: pricing ($0.01 USDC per call), the x402 payment mechanism inside the call, the fact that an unpaid call is what performs validation, and that failed calls aren't charged. This is exactly the cost and failure-policy information an agent needs before invoking a paid open-world tool.

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?

Front-loaded with the user-facing question and the core validation summary, with pricing and usage tucked at the end where it belongs. It is dense but every clause carries information; the long middle sentence is packed but not padded.

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?

Despite having no output schema, the description explains what comes back — a fix per problem, a paste-ready corrected 402, and a grade matching the weekly report card. Combined with cost and trigger guidance, an agent has everything needed 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?

Only one parameter and schema coverage is 100%, so the schema already documents the required public https URL. The description adds no format, syntax, or constraint detail beyond what the schema provides, so the baseline 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?

States a specific verb and resource — checks an x402 endpoint for Bazaar indexing — and enumerates exactly what is validated (402 PAYMENT-REQUIRED header, discovery metadata, schemas, description limits, service name). The opening question and the 'listing lint' framing distinguish it from siblings like conformance_check or buyer_check.

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?

'Use when an agent needs to lint an x402 listing before its first settled payment' gives a clear triggering condition and timing. It doesn't explicitly exclude or route against the numerous sibling check tools, so it stops short of full alternative guidance.

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