Convert an amount from one currency to another at the latest ECB reference rate. Returns the rate, the converted result, and the rate date.
| Name | Required | Description | Default |
|---|---|---|---|
| to | Yes | Target 3-letter currency | |
| from | Yes | Source 3-letter currency | |
| amount | Yes | Amount in the 'from' currency to convert. Send it as a number, not a string. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and it discloses the data source (ECB reference rate), the action's nature (latest-rate conversion), and the exact return fields. It does not discuss edge cases like unsupported currencies, but for a simple calculator-like tool this is adequate.
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 concise sentences, front-loaded with the primary action, and each sentence adds information: what it converts and what it returns. No wasted words.
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 3-parameter read-only conversion tool with a fully documented schema, the description gives the source, the rate type, and the return values. There is no missing information an agent needs to invoke it correctly.
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 input schema already documents each parameter fully at 100% coverage. The description restates the conversion relationship between `amount`, `from`, and `to` but does not add meaningfully 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 states a clear action ('Convert an amount'), the resource (currency amounts), and the specific time scope ('latest ECB reference rate'). This distinguishes it from historical or time-series sibling tools without ambiguity.
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 gives clear context: use this for current-rate conversions, as opposed to historical or time-series tools. It does not explicitly name sibling alternatives or say when not to use it, so it misses the top bar.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
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.