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

The description adds a useful behavioral note: '5 free trial calls per signed wallet', which hints at wallet-based access and billing. However, with no annotations, the description carries the full burden and still does not disclose whether the operation is read-only, what the response contains, or what happens when no match is found.

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 short and front-loaded with the core purpose, and the trial-call note is relevant extra context. It loses a point only for opening with the redundant tool-name prefix 'x402-country:'.

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 simple lookup tool this is minimally viable, but it lacks detail about the output format, the wallet-signing requirement beyond 'free trial', and how to disambiguate between iso, code, and country parameters. These gaps matter because no output schema or annotations exist to fill them.

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 baseline is 3. The description mentions ISO code, which aligns with the 'iso' parameter, but it does not clarify how 'code' and 'country' relate to 'iso', and all three parameters are optional with no guidance on which is preferred.

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 phrase 'Country by ISO code' indicates the resource (country) and the lookup key (ISO code), so an agent can infer a country lookup operation. It lacks an explicit verb like 'get' or 'lookup', but its meaning is clear enough and it hints at distinguishing inputs from related country tools such as x402-country-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 provided about when to use this tool versus alternatives like x402-country-code, x402-country-brief, or x402-capital-city. The description gives no selection criteria, no exclusions, and no context for choosing among the three parameters.

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