{ "openapi": "3.1.1", "info": { "title": "Historical FX Chart API", "version": "1.0.0", "summary": "Chart exchange rates over time from ECB data: min, max, average, change, volatility and CSV export.", "description": "Every endpoint performs the same calculation as the human page and returns inputs, result, units, assumptions, sources, warnings and computedAt. MCP endpoint: /mcp." }, "servers": [ { "url": "https://historicalfxchart.usefulweb.site" } ], "paths": { "/api/v1/calculate": { "post": { "operationId": "calculate", "summary": "Chart exchange rates over time from ECB data: min, max, average, change, volatility and CSV export.", "description": "Pick a base currency, one or more quote currencies and a date range (back to 1999). The tool loads the ECB’s daily euro reference rates, builds the cross rates, draws a line chart (indexed to 100 to compare several pairs) and reports start, end, minimum, maximum, average, change and annualised volatility, with a CSV download.\n\nMethodology:\n- Daily reference rates (units per euro) are loaded from the ECB Data Portal SDMX API as CSV (series D..EUR.SP00.A, only the requested currencies and dates) and cached; ranges ending more than a week ago are cached permanently, recent ranges per day.\n- Cross rate base/quote on each publication day = rate(quote) ÷ rate(base); days where either leg is missing are skipped. EUR legs are 1.\n- Statistics: first and last observation, minimum and maximum with dates, arithmetic mean, change = last ÷ first − 1, annualised volatility = standard deviation of daily log returns × √252.\n- Indexed view: every pair divided by its first value × 100, so pairs with very different levels (e.g. JPY and GBP) can be compared.\n\nReference rates for information; they are not the rates at which you could have traded.", "tags": [ "money" ], "x-mcp-tool": "historical_fx_chart", "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/HistoricalFxChartInput" }, "examples": { "example1": { "summary": "EUR/USD and EUR/GBP over 2024 (indexed)", "value": { "base": "EUR", "quotes": "USD, GBP", "start": "2024-01-01", "end": "2024-12-31" } }, "example2": { "summary": "USD/JPY in 2023", "value": { "base": "USD", "quotes": "JPY", "start": "2023-01-01", "end": "2023-12-31", "png": false } } } } } }, "responses": { "200": { "description": "Calculation result envelope.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/HistoricalFxChartResult" } } } }, "400": { "description": "Malformed JSON body.", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "422": { "description": "Invalid input (see errors[]).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "429": { "description": "Rate limit exceeded (see Retry-After).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } } } } }, "/api/v1/tool": { "get": { "operationId": "getToolDefinition", "summary": "Inputs, output schema and examples for this tool", "responses": { "200": { "description": "Tool definition.", "content": { "application/json": { "schema": { "type": "object" } } } } } } } }, "components": { "schemas": { "Problem": { "type": "object", "description": "RFC 9457 problem details. 422 responses include per-field `errors`.", "required": [ "type", "title", "status", "detail" ], "properties": { "type": { "type": "string" }, "title": { "type": "string" }, "status": { "type": "integer" }, "detail": { "type": "string" }, "code": { "type": "string" }, "errors": { "type": "array", "items": { "type": "object", "required": [ "field", "message" ], "properties": { "field": { "type": "string" }, "message": { "type": "string" } } } } } }, "HistoricalFxChartInput": { "type": "object", "additionalProperties": false, "properties": { "base": { "title": "Base currency", "description": "The rate shows how many units of the quote currency one unit of the base buys.", "type": "string", "maxLength": 3, "default": "EUR" }, "quotes": { "title": "Quote currencies", "description": "Up to 6 ISO codes, comma-separated.", "type": "string", "maxLength": 100, "default": "USD, GBP" }, "start": { "title": "From", "description": "Default: one year before the end date. Earliest 1999-01-04.", "type": "string", "format": "date" }, "end": { "title": "To", "description": "Default: today.", "type": "string", "format": "date" }, "normalise": { "title": "Index to 100 at the start", "type": "string", "enum": [ "auto", "yes", "no" ], "default": "auto" }, "png": { "title": "Also create a PNG image", "type": "boolean", "default": true } }, "required": [ "base", "quotes" ] }, "HistoricalFxChartResult": { "type": "object", "additionalProperties": false, "required": [ "schemaVersion", "tool", "computedAt", "inputs", "summary", "result", "units", "assumptions", "sources", "warnings", "presentation", "links" ], "properties": { "schemaVersion": { "type": "string", "const": "1.0" }, "tool": { "type": "object", "additionalProperties": false, "required": [ "id", "name", "version" ], "properties": { "id": { "type": "string" }, "name": { "type": "string" }, "version": { "type": "string" } } }, "computedAt": { "type": "string", "format": "date-time" }, "inputs": { "type": "object", "description": "Normalised inputs actually used, including applied defaults." }, "summary": { "type": "string" }, "result": { "type": "object", "additionalProperties": false, "required": [ "base", "quotes", "start", "end", "normalised", "pairs", "svg", "png", "dataUrl" ], "properties": { "base": { "type": "string" }, "quotes": { "type": "array", "items": { "type": "string" } }, "start": { "type": "string" }, "end": { "type": "string" }, "normalised": { "type": "boolean" }, "pairs": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "pair", "base", "quote", "observations", "start", "end", "min", "max", "average", "changePercent", "annualisedVolatilityPercent" ], "properties": { "pair": { "type": "string" }, "base": { "type": "string" }, "quote": { "type": "string" }, "observations": { "type": "integer" }, "start": { "type": "object" }, "end": { "type": "object" }, "min": { "type": "object" }, "max": { "type": "object" }, "average": { "type": "number" }, "changePercent": { "type": "number" }, "annualisedVolatilityPercent": { "type": [ "number", "null" ] } } } }, "svg": { "type": "object", "additionalProperties": false, "required": [ "artifactId", "filename", "mime", "bytes", "sha256", "path" ], "properties": { "artifactId": { "type": "string" }, "filename": { "type": "string" }, "mime": { "type": "string" }, "bytes": { "type": "integer" }, "sha256": { "type": "string" }, "path": { "type": "string", "description": "Download path on the same site (valid for about 2 hours)." } } }, "png": { "anyOf": [ { "type": "object", "additionalProperties": false, "required": [ "artifactId", "filename", "mime", "bytes", "sha256", "path" ], "properties": { "artifactId": { "type": "string" }, "filename": { "type": "string" }, "mime": { "type": "string" }, "bytes": { "type": "integer" }, "sha256": { "type": "string" }, "path": { "type": "string", "description": "Download path on the same site (valid for about 2 hours)." } } }, { "type": "null" } ] }, "dataUrl": { "type": "string", "description": "ECB Data Portal request used." } } }, "units": { "type": "object", "additionalProperties": { "type": "string" } }, "assumptions": { "type": "array", "items": { "type": "string" } }, "sources": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "title" ], "properties": { "title": { "type": "string" }, "url": { "type": "string" }, "publisher": { "type": "string" }, "retrievedAt": { "type": "string" }, "note": { "type": "string" } } } }, "warnings": { "type": "array", "items": { "type": "string" } }, "presentation": { "type": "array", "items": { "type": "object" }, "description": "Display blocks used by the human page (same data)." }, "links": { "type": "object", "additionalProperties": false, "required": [ "human", "api", "openapi", "methodology" ], "properties": { "human": { "type": "string", "format": "uri" }, "api": { "type": "string", "format": "uri" }, "openapi": { "type": "string", "format": "uri" }, "methodology": { "type": "string", "format": "uri" } } } } } } } }