Get API usage

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

The annotation readOnlyHint=true already signals a safe read operation, and the description goes beyond that by specifying exactly what data is shown (API calls, AI generation calls, overage calls, tier limits) and clarifying the scope (current billing period, configured API key). This adds useful behavioral context without contradicting the annotation.

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, information-dense sentence that is front-loaded with the verb and resource, and it lists specific metrics without any fluff. It earns its place entirely.

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, a readOnlyHint annotation, and an output schema (per context), the description fully conveys the tool's purpose and the information it returns. It does not omit any critical details for a simple usage-monitoring tool.

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, so there is no parameter schema to elaborate on. The baseline for 0 params is 4, and the description appropriately focuses on the output rather than parameters, which is sufficient.

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 uses a specific verb 'Show' and clearly identifies the resource (billing-period usage and limits for the configured API key) with concrete details (API calls, AI generation calls, overage calls, tier limits). This differentiates it from sibling tools like list_sets or generate_cards, which serve different purposes.

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 implied usage is for checking current usage and limits, but the description does not explicitly state when to use this tool versus alternatives or mention any exclusions. It lacks direct guidance on when to invoke this tool instead of others.

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