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

Goes well past the readOnlyHint/openWorldHint annotations by disclosing that it is a POST, that it costs $0.01 USDC per call, and exactly how the x402 payment challenge works: an unpaid call returns payment requirements, then retry with X-PAYMENT or PAYMENT-SIGNATURE headers or params._meta["x402/payment"]. That payment/auth behavior is the critical hidden trait of this tool and is fully surfaced.

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 action and accepted inputs, then the return values, then the payment mechanics, in that order of decision importance. The payment sentences are long but each carries operationally necessary detail rather than filler.

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?

With no output schema, the description does its job by naming the PASS/WARN/FAIL verdict shape and the checks performed, plus the payment flow. Remaining gaps are minor: whether url/header/body are mutually exclusive or combinable, and what the undocumented 'expected' object is for.

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 75%, and the description adds the key meaning the schema lacks: url, header, and body are three alternative input modes for the same payload, which an agent would otherwise have to infer. The 'expected' parameter (the one undescribed property) is not covered anywhere, so the mapping is not fully complete.

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: lint an x402 paid endpoint by URL, raw PAYMENT-REQUIRED header, or 402 JSON body, and returns PASS/WARN/FAIL checks. It enumerates the exact checks (version, networks, assets, atomic amounts, payTo, timeouts, EIP-712 extra) so it is unmistakable against siblings like config_lint or schema_diff.

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 says when this applies, validating x402 v1/v2 payment requirements, and explicitly excludes settlement with 'Static check, no settlement.' It also explains the correct invocation sequence if the first call returns a 402. It doesn't name alternative tools, but the scope is narrow enough that the context is clear.

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