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

With no annotations provided, the description must carry the full burden of behavioral disclosure. It simply states 'Historical spot price data' without mentioning return format, default range (1Y), rate limits, or any other behavior beyond the basic definition. This is minimal and does not add context beyond what the name already implies.

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, front-loaded with the core purpose. There is no redundant language or filler; every word contributes to the meaning.

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?

The tool is simple with two parameters, both enums with schema descriptions. However, there is no output schema, and the description does not specify the return format, default range, or any edge cases. It is minimally adequate but leaves gaps for a user unfamiliar with the tool.

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%, so the baseline is 3. The description's phrase 'for a precious metal over a time range' merely paraphrases the parameter descriptions and adds no new semantic detail about metal values or range options. It neither enhances nor detracts from the schema.

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 the tool's function: it retrieves historical spot price data for a precious metal over a time range. The verb 'get' is implied, and the resource and scope are explicit, distinguishing it from sibling tool 'get_spot_prices' which likely provides current prices.

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 implies usage for historical data retrieval but does not explicitly state when to use it over alternatives like 'get_spot_prices'. It provides context (time range, metal) but lacks explicit when-to-use or when-not-to-use guidance.

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