fx_period_rate

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

With no annotations, the description carries the burden of behavioral disclosure. It discloses that the return shape matches fetch_data and that dates follow ISO format, which is useful. It does not mention read-only behavior, authentication, pagination, or error handling, so the behavioral picture is incomplete.

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 three sentences with no filler: the convention mapping, date format, and return shape are each covered in one efficient sentence. It is well-structured and front-loads the most important 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 tool with no annotations, no output schema, and no parameter descriptions, the description provides key domain context and a useful link to fetch_data. However, it omits important details such as currency-code format, frequency/limit semantics, and explicit differentiation from fx_spot, so an agent might still make incorrect assumptions when calling it.

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 0%, so the description must compensate. It explains the non-obvious 'convention' parameter and date format, but leaves currency, start, end, freq, and limit mostly to inference. For a six-parameter tool, this is not enough compensation for the missing schema descriptions.

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 identifies the tool as returning Euro reference rates and distinguishes between 'average' and 'end_of_period' conventions, which makes the resource and its main use concrete. It lacks an explicit verb phrase and does not directly contrast itself with fx_spot, but the purpose is still clear enough for an agent to separate it from spot-rate tools.

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 provides explicit convention guidance: use 'average' for flows and 'end_of_period' for stocks, and it specifies ISO date formatting. However, it does not explicitly say when to choose this tool over sibling tools like fx_spot or fetch_data, so tool-selection context is implied rather than stated.

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