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

The description adds meaningful behavioral detail beyond annotations: free/no payment, no authentication required, any arguments are ignored, repeated calls return identical results, no filtering/pagination/configuration, and data source is local server config. The read-only and idempotent annotations are reinforced and expanded with practical operational context, enabling the agent to predict call behavior confidently.

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?

Although relatively detailed, every sentence earns its place: free/auth status, read-only/idempotent behavior, parameter handling, return content, use case, and explicit exclusions. The core purpose and no-arguments fact are front-loaded, and the organization flows naturally from behavior to usage 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 list tool with an explicit output schema and rich annotations, the description fully covers what an agent needs: access requirements, return content, side-effect safety, the canonical endpoint reference, and disambiguation from both sibling tools. Nothing essential is missing.

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 coverage is 100%, so the baseline is 4. The description adds useful semantics by explicitly confirming that any arguments are ignored and that calling without arguments returns the full catalog. This prevents agents from attempting to pass meaningless parameters.

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?

Names a specific verb and resource ('List available models and their prices') and clearly separates itself from siblings by stating it returns the catalog rather than generating text or estimating cost. The purpose is unambiguous and differentiates this tool from chat_completions and get_price_estimate.

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 states when to use it ('inspect models and prices before calling the paid chat_completions tool') and when not to use it ('do not use it to generate text' or 'estimate cost'), naming the appropriate alternatives in both exclusions. The usage guidance is direct and actionable.

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