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

No annotations are provided, so the description carries the behavioral burden; it does disclose that this is a read-only info tool returning endpoint URLs, prices, and an example. However it doesn't state that nothing is mutated, and with no annotations that is worth saying explicitly for a tool whose entire subject matter is payments.

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 purpose followed by a numbered two-rail breakdown and one sentence on the return payload, with zero filler. Every clause adds information.

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?

An output schema exists, so the description is not required to enumerate return fields; it still summarizes them (endpoint URLs, prices, minimal example) and names the exact headers (X-Zkapi-Proof, X-Zkapi-Session) an integrator needs. Complete for a zero-param info tool.

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 are zero parameters, so the baseline is 4. The description correctly implies a parameterless call and spends its space on the returned content instead.

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 (explain) and resource (the two private payment rails) and immediately scopes them to 'agents without an x402 wallet'. That scope plus the named sibling zkapi_get_kit lets an agent tell this info tool apart from the other zkapi tools.

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?

The description makes the audience condition explicit ('agents without an x402 wallet'), which is clear when-to-use guidance. It does not name an alternative or state when not to use it (e.g., use zkapi_get_kit if you already have a wallet), so it falls just short of a 5.

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