check_credits

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

With no annotations, the description carries the full behavioral burden. It discloses that this is a read-style lookup, that it is team-scoped, and that spend is measured over a 30-day window, but says nothing about auth/permission requirements, caching or freshness of the numbers, or whether the call itself consumes anything.

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 sentences, zero waste: the first defines the payload, the second defines the trigger. The purpose is front-loaded before the guidance.

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 zero-parameter lookup with no output schema, the description compensates by naming the returned facts (credits remaining, 30-day spend). It is nearly complete; only freshness/permission caveats are absent.

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 and the schema is an empty object, so there is nothing to document; per baseline this warrants a 4. The description correctly implies no input is needed.

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?

States a specific verb and resource ('Show how many AI Gateway credits are left') plus the exact data window for spend ('last 30 days'). It is unmistakably distinct from every sibling, which are all generative/edit operations.

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?

Explicitly tells the agent when to call it: 'Use it before big jobs (many videos) to check there is enough.' No alternatives or when-not conditions are named, but there is no sibling that overlaps this function, so the omission is minor.

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