call_endpoint

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

Adds real information beyond the annotations: authentication and plan-enrollment requirements, that each invocation consumes upstream quota, and the non-obvious fact that maxItems only trims returned array previews rather than the upstream request. It stops short of describing failure behavior or response shape for an open-world tool.

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?

Four dense sentences, purpose front-loaded, no filler. The telegraphic phrasing of 'Use schema parameter names exactly' is terse to the point of ambiguity, but nothing is redundant.

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?

Covers auth, quota cost, and read-only nature well, which is the hard part for an open-world tool. But with no output schema, four undocumented parameters, and a nested passthrough object, an agent still lacks guidance on how apiId/operationId are obtained and what the returned payload looks like.

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 0%, so the description carries the full burden, yet it explains only maxItems meaningfully and gives a cryptic hint ('use schema parameter names exactly') about the passthrough parameters object. The two required parameters, apiId and operationId, are left completely unexplained in both schema and description.

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 and mechanism: fetch source data via a documented GET operation, which is clearly the execution counterpart to the discovery siblings. It never names those siblings (search_apis, search_endpoints, describe_endpoint) or says the operation must have been resolved first, so differentiation is only implicit.

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?

Prerequisites (RAPIDAPI_KEY, plan enrollment) and the cost model (one call consumes upstream quota) are given, which helps an agent decide whether it can call at all. However there is no explicit statement of when to prefer this over the sibling discovery tools, nor which operation types are out of scope beyond the implied GET-only restriction.

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