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

With no annotations, the description carries the full burden. It usefully discloses that results are sorted 'most used first' and defines tx_count_7d, which adds real behavioral context. However it omits any note on credit consumption, rate limits, or pagination beyond the schema's limit.

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 tight sentences with the key scoping caveat and return-shape summary front-loaded. Dense and informative with little waste, though the parenthetical for tx_count_7d adds length.

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?

With no output schema, the description compensates by previewing the return payload (listings with endpoint counts, prices, tx_count_7d) and ordering. Combined with 100% schema coverage, an agent has enough to call it correctly; missing annotations on read-only safety are a minor gap for a clearly read-shaped search 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?

Schema description coverage is 100%, so limit, query, and category are already documented in the schema. The description adds no parameter syntax or matching-rule detail beyond what the schema provides, so baseline 3 applies.

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 (Search) and resource (external x402-protected APIs), and clarifies scope with 'not operated by APIHub, but callable via credits.' This implicitly separates it from the sibling apihub_search (internal), though it never names that alternative explicitly.

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 'external' qualifier implies when to reach for this over apihub_search or apihub_list_services, but there is no explicit when-to-use or when-not-to-use guidance. Usage must be inferred from context.

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