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

With no annotations, the description partially discloses behavior by stating it returns listings with endpoint counts, prices, and on-chain activity, and that APIs are callable via credits. However, it does not mention whether credits are consumed per search, authentication requirements, rate limits, or any side effects. The read-only nature is implied by 'search' and 'returns listings' but not explicit.

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?

Two sentences, the first states the action and scope, the second summarizes return payload. Every word adds value, no redundancy.

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?

The description explains the search scope (external APIs), cost context (credits), and return fields (endpoint counts, prices, on-chain activity). With no output schema, this return summary is helpful. However, it could mention that limit/query/category are optional filters, though those are in the schema. Overall adequate for a search tool with no required parameters.

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?

All three parameters (limit, query, category) are fully described in the schema with descriptions. The tool description does not add any parameter semantics beyond the schema, so baseline 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?

Description clearly states the tool searches external x402-protected APIs, specifying that these are not operated by APIHub and callable via credits. This distinguishes it from apihub_search which likely searches APIHub-owned services.

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?

Provides clear context that this is for external APIs and consumes credits, implying use when searching third-party APIs rather than internal ones. However, it does not explicitly name apihub_search as an alternative or state when not to use it.

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