FX API reference
Current rates, currency conversion, and history through REST and MCP.
All three operations are live. They use one Narwhal key and the same account quota.
Three operations
| Operation | REST path | MCP tool |
|---|---|---|
| Current rates | /v1/fx/rates/{base} | fx_get_rates |
| Currency conversion | /v1/fx/convert | fx_convert_currency |
| Historical rates | /v1/fx/rates/{base}/observations | fx_get_rate_history |
Shared rules
- One base unit equals the returned quote rate.
- Rates and amounts are decimal strings.
- Current rates keep their own timestamp and stale state.
- REST and MCP use the same data and quota.
- Errors use the shared Narwhal problem shape.
Coverage
Current rates accept supported circulating ISO 4217 currencies. History begins at different dates by currency and keeps genuine gaps.