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

No annotations are provided, so the description carries the full burden of behavioral disclosure. The only non-purpose behavior mentioned is the quota note ('5 free trial calls per signed wallet'), which implies a payment/wallet requirement but does not explain what happens on call: whether a report is returned, whether a review is async, or what cost applies after the trial. The core behavior of the call itself is undisclosed.

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 description is two short segments with the purpose front-loaded ('Review API design') followed by the trial-call note. There is no filler or repetition of schema content, though the 'API Review:' prefix is somewhat redundant with the tool name.

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 tool with no annotations, no output schema, and three vaguely-described optional inputs, the description is under-specified. It does not explain what a 'review' produces (score, issues list, report), how the wallet requirement works, or how an agent should construct a valid request. The free-trial note hints at constraints but leaves the core operational model unclear.

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 description coverage is 100%, so the schema documents each parameter ('Api to process', 'Code to process', 'Spec to process'), meeting the baseline. However, the descriptions are minimal and the tool description adds nothing about how the parameters relate — for instance, whether api, code, and spec are alternatives, combined inputs, or which one is expected for a design review. The agent gets no help selecting among three optional parameters.

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-object pair: 'Review API design.' This goes slightly beyond the name by specifying what is reviewed (design) rather than the API itself, and it is distinguishable from siblings like x402-ai-code-review (code review) and x402-api-key-detect. It is concise but could be clearer about whether it reviews a spec, a live endpoint, or code.

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?

No guidance is given on when to use this tool versus alternatives. The sibling list contains many adjacent tools (x402-ai-audit, x402-code-diagnose, x402-smart-contract-audit, x402-ai-code-review), and nothing here explains which scenario calls for API design review. There is no 'if you need X, use this' signal, so an agent must guess based on the name alone.

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