{ "openapi": "3.1.1", "info": { "title": "Hidden Fee Finder API", "version": "1.0.0", "summary": "Paste a quote, contract or invoice and see every fee, tax, penalty and add-on.", "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://hiddenfeefinder.usefulweb.site" } ], "paths": { "/api/v1/calculate": { "post": { "operationId": "calculate", "summary": "Paste a quote, contract or invoice and see every fee, tax, penalty and add-on.", "description": "Paste the lines of a quote, rental contract, booking or invoice (English or German). Hidden Fee Finder extracts the amounts, classifies each line with transparent keyword rules (base price, fee, tax, surcharge, penalty, deposit, discount, insurance/add-on, recurring), flags conditional penalties and optional add-ons, and shows how much of the total is not the base price.\n\nMethodology:\n- Each non-empty line is scanned for amounts. A number counts as money if it has a currency marker (€, $, £, EUR, USD, GBP, CHF…), exactly two decimals, or ends the line; the last such amount on a line is used. A number followed by % is a percentage.\n- Number formats: with both separators the last one is the decimal mark; \"1,234\" (comma + 3 digits) is read as a thousands separator in auto mode, \"12,50\" as a decimal; choose a fixed format to override.\n- Categories are assigned by ordered keyword rules (total → penalty → deposit → discount → tax → insurance/add-on → surcharge → fee → recurring → base). The first matching keyword is shown. Lines without any keyword default to base price.\n- Flags: conditional (late, cancellation, early termination, if, per day, wenn, falls, Verzug, pro Tag…), recurring (monthly, per year, subscription, monatlich…), optional/hidden (optional, pre-selected, recommended, auto-renew, empfohlen, voreingestellt…), included tax (incl./inkl./included).\n- Payable total = base + fees + taxes + surcharges + insurance/add-ons + recurring + discounts. Excluded: deposits (refundable), conditional lines (only if triggered), total lines, and taxes marked as included.\n- Percent-only lines: taxes are applied to the sum of all other included lines; other percentages are applied to the base total.\n- Non-base share = (payable total − base − discounts) ÷ payable total.", "tags": [ "money" ], "x-mcp-tool": "hidden_fee_finder", "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/HiddenFeeFinderInput" }, "examples": { "example1": { "summary": "Hotel booking with resort fee and conditional charges", "value": { "currency": "USD", "text": "Room rate, 3 nights: $420.00\nResort fee (mandatory): $105.00\nCity tax: 6%\nTravel insurance (pre-selected, optional): $29.99\nLate checkout fee if after 12:00: $50.00\nSecurity deposit (refundable): $200.00\nMember discount: -$21.00\nTotal: $566.03" } }, "example2": { "summary": "German rental quote", "value": { "currency": "EUR", "numberFormat": "de", "text": "Grundpreis Miete Transporter 1 Tag 89,00 €\nBearbeitungsgebühr 15,00 €\nWochenendzuschlag 20,00 €\nVollkaskoversicherung optional 24,90 €\nKaution 300,00 €\nVertragsstrafe bei verspäteter Rückgabe pro Tag 75,00 €\nGesamtbetrag inkl. 19% MwSt. 148,90 €" } } } } } }, "responses": { "200": { "description": "Calculation result envelope.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/HiddenFeeFinderResult" } } } }, "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" } } } } } }, "HiddenFeeFinderInput": { "type": "object", "additionalProperties": false, "properties": { "text": { "title": "Quote / contract / invoice lines", "description": "One cost per line. Supported amount formats: 1,234.56 / 1.234,56 / €12 / 12 EUR / 12,50 € and percentages like 19% or 2.5 %.", "type": "string", "maxLength": 50000 }, "items": { "title": "Or: line items", "description": "Optional alternative to pasting text. Rows are appended after the pasted lines.", "type": "array", "maxItems": 100, "items": { "type": "object", "additionalProperties": false, "properties": { "description": { "title": "Description", "type": "string" }, "amount": { "title": "Amount", "type": "number" } }, "required": [ "description", "amount" ] } }, "currency": { "title": "Currency", "type": "string", "maxLength": 8, "default": "EUR" }, "numberFormat": { "title": "Number format", "type": "string", "enum": [ "auto", "en", "de" ], "default": "auto" } }, "required": [] }, "HiddenFeeFinderResult": { "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": [ "currency", "lines", "totals", "statedTotal", "statedTotalDifference", "hiddenOrOptional", "conditionalCharges" ], "properties": { "currency": { "type": "string" }, "statedTotal": { "type": [ "number", "null" ], "description": "Amount on the last line recognised as a total, if any." }, "statedTotalDifference": { "type": [ "number", "null" ], "description": "Stated total − computed payable total." }, "totals": { "type": "object", "additionalProperties": false, "required": [ "base", "fees", "taxes", "surcharges", "insuranceAddons", "recurring", "discounts", "payableTotal", "nonBaseCosts", "nonBaseSharePercent", "deposits", "conditionalPotential", "upfrontCashInclDeposits" ], "properties": { "base": { "type": "number" }, "fees": { "type": "number" }, "taxes": { "type": "number" }, "surcharges": { "type": "number" }, "insuranceAddons": { "type": "number" }, "recurring": { "type": "number" }, "discounts": { "type": "number", "description": "Negative number." }, "payableTotal": { "type": "number", "description": "Sum of all lines included in the total (excludes deposits, conditional charges, totals and taxes stated as included)." }, "nonBaseCosts": { "type": "number", "description": "fees + taxes + surcharges + insurance/add-ons + recurring (non-base lines)." }, "nonBaseSharePercent": { "type": "number", "description": "nonBaseCosts ÷ payableTotal × 100." }, "deposits": { "type": "number" }, "conditionalPotential": { "type": "number", "description": "Sum of conditional charges (only due if triggered)." }, "upfrontCashInclDeposits": { "type": "number" } } }, "lines": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "lineNumber", "text", "amount", "percent", "amountSource", "category", "matchedKeyword", "recurring", "recurringKeyword", "conditional", "conditionalKeyword", "optional", "optionalKeyword", "includedTax", "includedInTotal" ], "properties": { "lineNumber": { "type": "integer" }, "text": { "type": "string" }, "amount": { "type": [ "number", "null" ] }, "percent": { "type": [ "number", "null" ] }, "amountSource": { "type": "string", "enum": [ "stated", "derived-from-percent", "none" ] }, "category": { "type": "string", "enum": [ "base", "fee", "tax", "surcharge", "penalty", "deposit", "discount", "insurance-addon", "recurring", "total", "info" ] }, "matchedKeyword": { "type": [ "string", "null" ], "description": "Keyword that triggered the category (null = default base price)." }, "recurring": { "type": "boolean" }, "recurringKeyword": { "type": [ "string", "null" ] }, "conditional": { "type": "boolean" }, "conditionalKeyword": { "type": [ "string", "null" ] }, "optional": { "type": "boolean" }, "optionalKeyword": { "type": [ "string", "null" ] }, "includedTax": { "type": "boolean", "description": "Tax stated as already included (e.g. \"incl. VAT\"); not added again." }, "includedInTotal": { "type": "boolean" } } } }, "hiddenOrOptional": { "type": "array", "items": { "type": "string" } }, "conditionalCharges": { "type": "array", "items": { "type": "string" } } } }, "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" } } } } } } } }