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

No annotations are present, so the description carries full behavioral disclosure. It reveals that the request is free and does not count against the daily limit, notes that 'requests_today' is best-effort from KV and resets at UTC midnight, and gives latency estimates. It also clarifies auth via the Authorization header.

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 moderately long but highly structured with sections for use cases, returned fields, cost, and latency. Bullet points make it scannable, and there is no redundancy or filler.

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?

Given the tool has no parameters and no output schema, the description fully compensates by specifying all return values, including edge cases like null last_used and unlimited enterprise limit. Usage guidance and cost/latency details make selection and invocation unambiguous.

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?

With zero parameters in the schema, the description states 'No body or query parameters' and clarifies that auth comes from the Authorization header, which adds meaning beyond the empty schema. It also enumerates the exact return fields with types and edge cases.

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 opens with a specific verb 'Returns' and enumerates exactly what is returned for the API key used in this request. It distinguishes from sibling tools like revoke_api_key and create_free_key by focusing on the calling key's quota and metadata.

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?

Explicit 'Use this tool when' and 'Do NOT use this tool when' sections lay out appropriate scenarios (monitor quota, check tier/limit, confirm active) and exclusions (managing multiple keys, needing tracker data) with an alternative ('use the tracker endpoints instead').

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