usage_stats

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

With no annotations, the description must carry the full burden. It only adds 'No API key required' as a behavioral trait. It does not disclose whether the operation is read-only, idempotent, or has side effects, which is insufficient for a stats 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?

Two concise sentences that front-load the core action. No redundant phrases or unnecessary details.

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 tool has no output schema, yet the description does not describe the return format or fields. Given two simple parameters, this is a moderate gap; a user might need to invoke to understand output.

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 coverage is 100% with enum descriptions. The description echoes the grouping options but adds no new meaning beyond the schema, such as explaining what 'cache' or 'anomaly' grouping entails.

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 retrieves token usage statistics and API costs, with grouping by model/project/day. It distinguishes itself from siblings like usage_anomalies and usage_breakdown by being the general stats endpoint.

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 description implies use for checking consumption, but does not explicitly state when to use this tool versus specific siblings (e.g., usage_anomalies for anomalies). No exclusion criteria or alternatives are mentioned.

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