check_credits

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

With no annotations, the description must carry the behavioral burden. It discloses that the tool is free, instant, non-generative, and requires a specific API key. It also mentions the starting credits and where to get a key. It doesn't describe error handling or output format, but for a zero-parameter balance check, the key behaviors are covered.

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, front-loaded with the primary purpose, then efficiently packs prerequisites, exclusions, and a resource link. Every sentence earns its place; no fluff.

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 tool with no output schema, the description is complete: it states what is checked, the authentication requirement, the non-generative nature, and how to obtain a key. An agent can call it correctly without further context.

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 100% schema coverage (empty object), so the baseline is 4. The description adds no parameter-specific info because none exist, but it does explain the context of the check (credit balance and image count) which is relevant to how the tool is invoked.

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 states a specific verb ('Check') and resource ('remaining you.bot credit balance'), and explicitly disambiguates from siblings by noting it 'does not generate anything.' This is distinct from generate_image and edit_image.

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 provides clear prerequisites (requires YOUBOT_API_KEY, not OpenAI key) and a hint of when to use it (free, instant, for checking balance). It doesn't explicitly say 'use before generate_image' but the exclusion 'does not generate anything' implies it's a preliminary check. Slight gap in explicit alternative routing.

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