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

With no annotations, the description carries the full burden and does well: it discloses the no-payment guarantee, that both GET and POST are exercised, and what the response contains (ids, severities, fixes). It stops short of mentioning auth requirements, rate limits, or side effects on the target server, so not a 5.

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 core action and the no-payment guarantee are front-loaded, and the parenthetical enumeration is dense but informative. It is one long sentence with a checklist, which is efficient though slightly hard to scan.

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?

No output schema exists, and the description compensates by describing the return shape (findings with ids, severities, fixes). For a two-parameter, read-only diagnostic, the remaining gaps — auth expectations and target-side effects — are minor but real.

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 coverage is 100%, so both parameters are already documented, including the 'auto: tries both' enum meaning. The description restates that GET and POST are both fetched but adds no syntax or format meaning beyond the schema, making 3 the correct 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?

Opens with a specific verb and resource — 'Unpaid lint of an x402 endpoint' — and enumerates exactly what is checked (challenge, transport, discovery files), so an agent knows precisely what the tool does. It never mentions the sibling lint_payment_required, so there is no explicit differentiation, which keeps it below a 5.

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?

'Unpaid' and 'Never pays. Free.' clearly establish this as a safe pre-flight check that can run without spending funds, which is a real usage signal. However, it gives no explicit when-not conditions and never routes the agent to or away from lint_payment_required.

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