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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses crucial behavior an agent could not infer: it is a paid call ($0.005 USDC via x402 inside the tool call), it makes one unpaid call to the target endpoint, failed calls are not charged, and it returns a fix per problem. Payment and billing semantics are exactly the kind of context annotations do not cover.

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?

It opens with the user's motivating question, then front-loads what is checked, then when to use it, then pricing. Every sentence adds distinct information (scope, trigger, cost, failure handling) with no repetition.

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 one-parameter tool with no output schema, the description covers trigger, cost, and failure behavior, and hints at return content ('a fix for each problem'). A slightly clearer statement of what the response contains would close the only remaining gap.

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?

There is a single required parameter with 100% schema description coverage ('Public https URL of the paid endpoint'), so the schema already carries the meaning. The description adds only the framing that the URL is an x402 endpoint to be linted, which is mild value on top of the baseline.

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 (checks/validates) and resource (an x402 endpoint's Bazaar listing) and enumerates exactly what is validated: 402 PAYMENT-REQUIRED header, discovery metadata, input/output schemas, description limits, and service name. This is clearly distinct from the analytics/rank siblings (buyer_panel, rank_check, demand_gaps).

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?

It gives a concrete trigger: 'Use when an agent needs to lint an x402 listing before its first settled payment.' That is a clear context for invocation. It does not, however, name an alternative tool or state when not to use it, so it falls short of explicit routing guidance.

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