Single-tool server with a clear action verb, good description, and valid JSON Schema. The tool naming (get_exchange_rate) follows the verb_noun pattern correctly. Description is 170 chars, within the 10 - 1024 baseline. All three parameters have descriptions and type definitions. However, the output schema is completely undocumented, users/agents cannot know what fields to expect (rates dict structure, date field format, etc.). Parameter descriptions mention 'latest' as a default but do not specify valid date format constraints (YYYY-MM-DD assumed but never stated). Error handling returns unstructured dicts with 'error' keys; no recovery guidance for agents. The tool is simple enough that the lack of pagination and result-limit documentation is acceptable (single exchange rate lookup, not a list operation).

• Document the output schema in the tool description or via a separate schema annotation. Example: 'Returns {"date": "YYYY-MM-DD", "from": "<currency>", "to": "<currency>", "rates": {"<target>": <number>}}'.
• Add format constraint to currency_date parameter. Change description to: 'The date for the exchange rate in YYYY-MM-DD format (e.g., 2024-01-15), or "latest" for the most recent available rate. Only business days are supported.'
• Implement input validation with actionable error messages. Example: 'Invalid currency code: "USDA". Did you mean "USD"? Supported codes: USD, EUR, GBP, JPY, ...'
• Enhance error responses with recovery hints. Example: Instead of {"error": "API request failed: ..."}, return {"error": "Currency conversion failed", "reason": "Invalid currency pair", "suggestion": "Check that both currency codes are valid ISO 4217 codes (e.g., USD, EUR). Supported currencies: USD, EUR, GBP, ..."}
• Consider adding a discovery tool (list_supported_currencies) if the Frankfurter API supports it, allowing agents to verify valid inputs before attempting conversion.

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry