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

The description 'Estimate cost' aligns with the readOnlyHint annotation, indicating a safe read operation. No additional behavioral traits are disclosed beyond what annotations provide, but there is no contradiction. With annotations covering the read-only nature, a baseline score of 3 is appropriate.

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 concise sentence with no waste. It is front-loaded with the main purpose. However, it could benefit from slightly more detail without becoming verbose.

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 5 optional parameters and an output schema, the description is too minimal. It does not explain how the cost is calculated (e.g., formula, whether it sums tokens or calculates per-request) or what the return format is. The output schema may cover return values, but the description itself leaves significant gaps.

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 100%, but parameter descriptions are minimal (just parameter names). The description adds no extra meaning beyond the schema, so a baseline score of 3 is correct.

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 clearly states it estimates cost from model pricing and token volumes, which is a specific verb+resource combination. It distinguishes from siblings like 'pricing_history' or 'find_cheapest' by focusing on calculation, though it could be more precise (e.g., total cost or per-request).

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?

No guidance is provided on when to use this tool versus alternatives like 'find_cheapest' or 'compare_models'. There is no mention of prerequisites, edge cases, or typical scenarios.

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