Price on a date

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

With no annotations, the description properly explains the function (lookup, no side effects), clarifies the meaning of 'covered=false', and indicates the output includes the price and source. It is transparent about what the tool does without contradictions.

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 concise (3 sentences) and front-loaded with the core purpose. Each sentence adds essential information: the output, use cases, and the special case of 'covered=false'. No wasted words.

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?

Despite lacking an output schema, the description explains the key output fields (price per million tokens, source, covered flag). For a simple lookup with 2 required parameters, this is sufficient to understand what the tool returns.

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 coverage is 100%, baselining at 3. The description adds value by explaining the purpose of 'model' (id or alias), 'date' (YYYY-MM-DD), and 'provider' (disambiguation), and clarifies the meaning of 'covered=false' in the output.

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 returns the price per million tokens in effect on a given date, specifically for point-in-time lookup to value past usage or see price changes. It distinguishes from siblings like 'current_price' and 'compare' by emphasizing historical lookup and noting the 'covered=false' flag.

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 explicitly advises to use it for 'valuing past usage' or 'seeing how a price changed over time', implying it's not for current prices. Although alternatives are not named, the sibling tools list provides context, making the usage reasonably clear.

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