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

Annotations already declare readOnlyHint and idempotentHint, so safety is covered. The description adds behavioral detail beyond that by specifying the data scope: 'every offer tracked by InferIndex', granularity options (daily/weekly min/max/last price, raw price changes), and the inclusion of the lab's official price over time.

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 with no filler. The first sentence front-loads the resource ('one model') and the return content; the second gives a compact usage rule for date selection. Every clause earns its place.

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?

There is no output schema, so the description needs to cover return content, which it does by listing USD min/max/last prices, raw changes, and official lab price. Missing details like ordering or pagination are minor and not essential for correct invocation.

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%, so baseline is 3. The description adds value by clarifying that the date parameters are alternatives ('Give either days, or from/to, or at'), which is not made explicit in the individual parameter descriptions. It does not need to repeat schema details, so 4 is appropriate.

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 explicitly states the tool returns 'Price history of one model', making the resource and scope clear. It contrasts with sibling tools like cheapest and compare_providers by focusing on historical tracking rather than comparisons or estimates, so an agent can distinguish it without opening schemas.

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 explains how to specify date windows ('Give either days, or from/to, or at'), which is parameter-level guidance. However, it does not explicitly state when to prefer this tool over search_models, cheapest, or compare_providers; the 'one model' phrase provides only weak inference rather than clear when-to-use guidance.

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