get_api_usage

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

Annotations already declare readOnlyHint and idempotentHint, so the agent knows it's a safe, read-only operation. The description adds the 'per budget' detail, which is useful context beyond annotations. However, it doesn't disclose what happens if there is no budget or how often the data refreshes, which could affect interpretation. No contradiction with annotations.

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 a single, focused sentence that front-loads the core purpose. Every word earns its place; it conveys the what, the metric (metered calls), the state (used/remaining), the timeframe (current period), and the granularity (per budget) without redundancy.

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 is simple (no parameters, no nested objects) and has an output schema, so the description doesn't need to detail return values. It covers the essential aspects an agent needs to call it correctly – what it returns and how it's organized. It could mention what happens if no budget is set, but that's a minor gap given the simplicity.

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 has zero parameters, and schema coverage is 100% (vacuously). The description explains the tool's output context (usage and remaining per budget), which is sufficient given no parameters need documentation. Since there are no parameters to explain, the description's mention of time period and budget adds value over the empty schema.

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 clearly states the tool reports metered API call usage and remaining quota per budget. It identifies a specific resource (API usage) and informative detail (used/remaining, current period, per budget), which distinguishes it from siblings like get_weather or compare_routes. However, it doesn't explicitly name a sibling it differentiates from, and the title 'API usage' is somewhat generic.

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 the tool is for checking API consumption quotas, which is clear enough for an agent to know when to use it. However, it doesn't explicitly state when not to use it or mention alternatives (e.g., if you need detailed logs or per-endpoint breakdowns). The sibling list doesn't help since they are unrelated to usage.

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