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

No annotations are provided, so the description carries the full burden of disclosing behavioral traits. It only states that credits are checked but does not explain whether the operation is read-only, what the response will contain, how a missing api_key is handled, or whether any side effects or rate limits apply.

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, front-loaded sentence with no redundant or filler content. Every word contributes to stating the tool's purpose, making it highly concise.

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?

With no output schema and no annotations, the description should explain what the agent can expect from the tool, such as the format of the credit count or how the api_key parameter is used. It only states the action, leaving the return value and default-key behavior unspecified.

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 description coverage is 0%, and the description only mentions 'API key' without elaborating on the api_key parameter's semantics, defaults, or behavior when omitted. Since the schema documents only the parameter name and default, the description adds minimal value and does not compensate for the low coverage.

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 ('Check') and a clear resource ('remaining credits for an API key'), which accurately states the tool's function. It is immediately distinguishable from the sibling tools, which suggest generation, ordering, and key collection operations rather than a credit balance lookup.

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 makes the context clear: use this tool when you need to know how many credits remain for an API key. It does not explicitly name alternatives or exclusions, but no sibling appears to offer a credit-check function, so the usage context is sufficiently evident.

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