Varrd

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

Adds cost transparency ('Free') and return value description ('credit balance', 'credit packs') beyond annotations. Annotations cover safety (readOnly, idempotent, non-destructive), but description usefully confirms the API call itself consumes no credits.

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 dense sentences: first states function and cost, second states usage context. No redundancy or schema repetition.

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?

Compensates for missing output schema by describing returned data (balance, packs). With rich annotations covering behavior and zero input complexity, description provides sufficient 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?

Zero parameters validates baseline of 4. No parameter semantic description needed or expected.

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?

Excellent specific verb ('Check') and resources ('credit balance', 'available credit packs'). Distinct from sibling 'buy_credits' (this queries, that purchases) and research tools.

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?

Explicit when-to-use: 'Call this before heavy operations to ensure you have sufficient credits.' Also clarifies cost model ('Free — no credits consumed') guiding invocation frequency.

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