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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description contributes beyond them by disclosing the master-API-key authorization prerequisite, a constraint an agent cannot infer from structured fields. It stops short of describing response scope or any rate-limit context of its own.

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?

Front-loaded single sentence plus a short auth note, both earning their place. The appended aisa-pricing boilerplate is not authored description content and adds noise, but the core text is tight.

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 zero parameters, an output schema present (so return values need no explanation), and annotations covering the safety profile, the description carries the remaining informational burden adequately by stating the auth requirement. Slightly more context about what stats are returned would be ideal but is not required given the output schema.

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 tool takes zero parameters, which is the documented baseline of 4. There is nothing parameter-wise for the description to compensate for, and schema coverage is complete.

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 gives a specific verb+resource: view API usage stats and rate limits. This is the only usage/rate-limit tool among the Apollo siblings, so it is distinguishable by resource even though no sibling is named. Clear, though it lacks explicit contrast with lookalike read tools.

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 intended use (checking usage and rate limits) is implied by the resource name, and the prerequisite 'Requires a master API key' is stated. However, there is no explicit when-to-use trigger and no named alternative or exclusion criteria.

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