Get foreign-exchange rates for a base currency on a specific past date (YYYY-MM-DD). ECB publishes rates on business days; a weekend/holiday date returns the most recent prior business day.
| Name | Required | Description | Default |
|---|---|---|---|
| base | No | 3-letter base (default USD) | |
| date | Yes | YYYY-MM-DD | |
| symbols | No | Optional comma-separated targets |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the full burden of behavioral disclosure. It explains the business day behavior for weekend/holiday dates, which is a useful behavioral trait. However, it does not mention that the tool is read-only, any authentication requirements, rate limits, or error handling. The transparency is moderate.
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 wasted words. The first sentence states the core purpose concisely, and the second adds a critical nuance (business day behavior). Every sentence 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?
Given the tool has three parameters and no output schema, the description could be more complete about the response format or error conditions. It covers the important date behavior but lacks details on what the response contains (e.g., rates relative to base) and potential errors (e.g., invalid date).
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% (all three parameters have descriptions in the schema), so the baseline is 3. The description adds context about the date format and base default but does not add new parameter-level details beyond what the schema provides. It does not enhance semantic understanding beyond 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 retrieves foreign-exchange rates for a base currency on a specific past date, using the verb 'Get' and identifying the resource. It adds context about ECB publication behavior. However, it does not explicitly differentiate from sibling tools like fx_timeseries or fx_rates, which reduces clarity.
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 context on date behavior (weekend/holiday returns prior business day) but does not offer explicit guidance on when to use this tool versus alternatives like fx_timeseries for multiple dates or fx_convert for conversions. The usage 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.
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Each tool targets a distinct operation: one-off conversion, currency listing, latest rates, historical rates, and time-series analysis. There is no meaningful overlap between any pair.
All tools share the fx_ prefix, but naming style is inconsistent: fx_convert is a verb, while fx_currencies, fx_rates, fx_historical, and fx_timeseries are nouns/adjectives. Consistent verb_noun names such as list_currencies or get_rates would improve predictability.
Five tools is well-scoped for an FX reference-rate server: one converter, one metadata endpoint, and three rate-lookup variants. Each tool serves a distinct, useful purpose with no bloat.
The surface covers the core FX use cases: listing supported currencies, latest rates, historical rates, time series, and amount conversion. No obvious missing operation is needed for the stated domain.