check_usage

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

No annotations are provided, so the description carries the full disclosure burden. It discloses the authentication requirement ('Requires an API key (INVOKIT_API_KEY environment variable)') and the monthly time scope, and the verb 'check' implies a non-mutating read. It does not describe failure behavior (e.g., what happens without the key) or rate-limit specifics, but the output schema covers the return structure. No contradiction with annotations exists since none are present.

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?

Three tight sentences, each earning its place: the first states the core purpose, the second discloses the environment-variable prerequisite, and the third gives the usage directive. The most important information is front-loaded, and there is zero filler or 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?

For a simple, parameterless status tool with an output schema present, the description covers the essentials: what is checked, what auth is required, and when to use it. Return values are already handled by the output schema, so the only gap is error/edge-case behavior, which is minor for a read-only usage check.

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 the schema needs no documentation. Per the rubric, zero-param tools default to a baseline of 4. The description adds no parameter detail (correctly, since there are none to describe) and the context signal confirms 100% schema coverage. Nothing is missing here.

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-resource pair: 'Check your current API usage, quota, and remaining calls for this month.' It names the exact resource being inspected (usage, quota, remaining calls) and scopes it to a time window ('this month'). It is clearly distinct from all siblings, which are tool/app/skill discovery and evaluation operations (search_tools, get_tool, get_metrics), so an agent can disambiguate it without reading schemas.

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 gives explicit when-to-use guidance: 'Use this before invoking tools to ensure you have remaining quota.' This is clear contextual direction for a pre-flight check. It does not name exclusions or alternatives, but none are needed since no sibling performs a usage check. The API-key requirement is also stated, reinforcing the preconditions for use.

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