check_x402_endpoint

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

No annotations exist, so the description carries the full burden and does it well: it discloses that exactly one request is sent, that it never pays, and that unmeasurable levels are reported as 'not measured' rather than failed. It omits auth requirements, rate limits, and side-effect details on the target endpoint beyond payment, keeping it short of 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?

Three tight sentences, front-loaded with purpose and the safety constraint, then the report semantics. Every clause earns its place, including the not-measured-vs-failed distinction.

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 explain the return shape conceptually (conformance ladder levels). It doesn't describe the report's structure or what a partial/errored check looks like, leaving a small gap for a tool whose value is its output.

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% and both parameters carry their own descriptions including default and GET guidance, so the description need not compensate. It adds only implicit context that the URL is a paid endpoint; no format or method semantics beyond the schema.

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 ('Check a paid x402 endpoint'), plus the scope constraint 'BEFORE paying it.' An agent knows exactly what this does and that it is non-committal. The lone sibling, link_receipt_to_settlement, is clearly a different operation, so no disambiguation is needed.

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?

'Check a paid x402 endpoint BEFORE paying it' gives clear situational guidance: use this as a pre-flight probe, not as a paid call. It does not name an alternative or state when not to use it, but with only one unrelated sibling there is little to route against.

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