Get currency conversion rate

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

The annotations already declare readOnlyHint, idempotentHint, and openWorldHint, covering safety and repeatability. The description adds a useful nuance that it returns the rate Billingo would apply, not necessarily a market rate. However, it does not describe rate dynamics, date sensitivity, or output details, so it adds only moderate behavioral context beyond the 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?

The description is a single, focused sentence that front-loads the core action and resource. Every word adds meaning, and there is no repetition of the title or obvious filler. It is optimally concise and scannable.

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 straightforward, read-only conversion-rate lookup with two required enum parameters and one optional date, the description together with the schema and annotations gives an agent enough to call the tool correctly. There is no output schema, but the return value is clearly implied by the description. A few details like exact response format or error conditions are absent, but they are 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?

The main description contains no parameter-level information, but schema_description_coverage is 100%. The schema provides clear descriptions for from, to, and date, including a valuable explanation of how to use the date parameter for historical documents. This meets the baseline expectation for a well-covered schema; the description itself adds no further parameter semantics.

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 states a specific verb ('Returns'), a specific resource ('conversion rate'), and a clear qualifier ('Billingo would apply'). It fully conveys what the tool does and is naturally distinguished from the sibling tools, none of which offer conversion rates.

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 main description does not explicitly state when to use this tool or when to prefer an alternative. Since no sibling tool provides conversion rates, this is less critical, but the usage context is only implied. The schema's date parameter description adds meaningful practical guidance for backdated documents, but that belongs to the structured schema rather than the tool description.

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