get_historical_exchange_rates

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

Description adds value beyond readOnlyHint annotation by detailing the fallback behavior (closest date before specified date) and the optional filtering via symbols. No contradictions with annotations.

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?

Three sentences covering purpose, fallback, and parameter requirements. No redundancy, efficiently organized.

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?

Account for 5 parameters and no output schema; description explains behavior but lacks details on return format or structure. Still adequate for selecting and invoking 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 description coverage is 100%, so the schema already documents each parameter. The description adds high-level context but does not introduce new semantics beyond reiterating filtering and date constraints.

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 historical exchange rates for a specific date or date range, using a specific verb and resource. It distinguishes from sibling tools like get_latest_exchange_rates and convert_* functions.

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?

It explains when the tool provides fallback rates and the required parameter combinations (specific date, start date, or date range). However, it does not explicitly contrast with sibling tools or state when not to use it.

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