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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds significant behavioral context: 'unknown' is an honest answer rather than a data gap, and it explains the Nigerian card limitations that make 'accepts Visa' misleading. This is exactly the kind of nuance an agent needs to interpret results correctly.

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 opens with the primary use case, immediately lists the returned dimensions, and closes with a short, valuable caveat about 'unknown' and Nigerian card limitations. Every sentence carries useful information, and the structure front-loads the most important semantic content.

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?

Despite lacking an output schema, the description enumerates all major return dimensions: naira pricing, card compatibility, local rails, local entity, geo-restriction, workaround, and pages_to_verify. It also defines the meaning of 'unknown' so an agent can correctly interpret ambiguous results. The single required parameter is fully described by the schema, so nothing essential is missing.

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?

The schema already documents the single 'name' parameter as 'product or service name, or its domain,' so schema coverage is 100%. The description restates 'named product or service' but adds no new format, examples, or syntax details. With full schema coverage, the baseline score of 3 is appropriate.

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 names a specific question ('can someone in Nigeria actually pay') and a specific resource ('a named product or service'), then enumerates the concrete dimensions it returns. This gives the tool a clear identity that distinguishes it from sibling tools like ranked_check_licence or ranked_compare. It is not a tautology and leaves no doubt about what the tool does.

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 gives a clear trigger condition: use it when you need to know whether a Nigerian can pay for a specific product or service, including naira pricing and local rails. It does not explicitly name alternatives or say when not to use it, but the scope is obvious enough that an agent can decide without opening sibling schemas.

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