mcp-ezpay-einvoice

MCP Server for Taiwan's ezPay E-Invoice API

Traditional Chinese (繁體中文)

Overview

An MCP (Model Context Protocol) server that exposes 7 AI-callable tools for the full Taiwan e-invoice lifecycle through the ezPay platform. Covers invoice issuance (B2B/B2C), triggering, voiding, allowances (credit notes/refunds), and querying -- all accessible to AI assistants like Claude via the standard MCP protocol.

Part of the Asgard AI Platform open-source ecosystem.

Features

• issue_invoice -- Issue B2B (business) or B2C (individual) e-invoices with full item detail, tax types, carriers, and donation codes
• trigger_invoice -- Trigger deferred or scheduled invoices for immediate issuance
• void_invoice -- Void issued invoices within the allowed reporting period
• issue_allowance -- Issue allowances (credit notes / partial refunds) against existing invoices
• trigger_allowance -- Confirm or cancel pending allowances
• void_allowance -- Void confirmed allowances
• query_invoice -- Query invoice details by invoice number or order number
• AES-256-CBC encryption -- Implements the ezPay encrypted form POST protocol (URL-encode, PKCS7 pad, AES encrypt, hex encode)
• CheckCode verification -- SHA-256 based response validation
• Dual environment -- Supports both test (cinv.ezpay.com.tw) and production (inv.ezpay.com.tw) environments

Prerequisites

• Python 3.10 or higher
• uv (recommended) or pip
• An ezPay merchant account with API credentials (MerchantID, HashKey, HashIV)
  • Test environment: register at https://cinv.ezpay.com.tw/
  • Production environment: register at https://inv.ezpay.com.tw/

Setup

# Clone the repository
git clone https://github.com/asgard-ai-platform/mcp-ezpay-einvoice.git
cd mcp-ezpay-einvoice

# Create virtual environment and install dependencies
uv venv && source .venv/bin/activate
uv pip install -e .

# Configure credentials
cp .env.example .env
# Edit .env with your ezPay merchant credentials

# Test connection
python scripts/auth/test_connection.py

Configuration

Usage

Claude Desktop / Claude Code Integration

This server integrates with Claude through the .mcp.json configuration file included in the repository:

{
  "mcpServers": {
    "ezpay-einvoice": {
      "command": "python",
      "args": ["mcp_server.py"],
      "cwd": "/path/to/mcp-ezpay-einvoice",
      "env": {
        "PYTHONPATH": "/path/to/mcp-ezpay-einvoice",
        "EZPAY_MERCHANT_ID": "your_merchant_id",
        "EZPAY_HASH_KEY": "your_hash_key",
        "EZPAY_HASH_IV": "your_hash_iv",
        "EZPAY_IS_PRODUCTION": "false"
      }
    }
  }
}

For Claude Desktop, add this configuration to your claude_desktop_config.json. For Claude Code, the .mcp.json file in the project root is auto-discovered.

CLI Testing

# Validate credentials and connectivity
python scripts/auth/test_connection.py

# Run all 7 tool E2E tests
python tests/test_all_tools.py

# Start the MCP server
python mcp_server.py

Usage Examples

Once the MCP server is running, an AI assistant (e.g. Claude) can call these tools on your behalf. Here are real-world scenarios showing what you say and how the AI responds.

"Help me issue an invoice for a customer who bought a test product"

You: 幫我開一張發票，客人買了一個測試商品 105 元含稅，要印紙本發票

AI calls:

issue_invoice(
  merchant_order_no = "ORDER20260404001",
  buyer_name        = "Test Buyer",
  category          = "B2C",
  tax_type          = "1",
  tax_rate          = 5,
  amt               = 100,
  tax_amt           = 5,
  total_amt         = 105,
  item_name         = "Test Product",
  item_count        = "1",
  item_unit         = "pc",
  item_price        = "105",
  item_amt          = "105",
  print_flag        = "Y",
  status            = "1",
)

Result: SUCCESS -- Invoice TE00000000 issued, amount NT$105, random code 9393. The response includes BarCode, QRcodeL, and QRcodeR for printing.

"Issue a B2B invoice with the buyer's tax ID"

You: 幫我開一張 B2B 發票給統編 54352706 的公司，品名是顧問服務費 10000 元加稅 500 元

AI calls:

issue_invoice(
  merchant_order_no = "B2B20260404001",
  buyer_name        = "範例科技股份有限公司",
  buyer_ubn         = "54352706",
  category          = "B2B",
  tax_type          = "1",
  tax_rate          = 5,
  amt               = 10000,
  tax_amt           = 500,
  total_amt         = 10500,
  item_name         = "顧問服務費",
  item_count        = "1",
  item_unit         = "式",
  item_price        = "10000",
  item_amt          = "10000",
  print_flag        = "Y",
  status            = "1",
)

Result: SUCCESS -- B2B invoice issued with buyer UBN 54352706. The printed invoice includes BarCode and QR codes for tax reporting.

"Issue a B2C invoice with phone barcode carrier"

You: 客人要存手機條碼載具 /ABC1234，不印紙本，品項是拿鐵咖啡 2 杯 65 元、巧克力蛋糕 1 個 85 元

AI calls:

issue_invoice(
  merchant_order_no = "POS20260404001",
  buyer_name        = "顧客",
  category          = "B2C",
  carrier_type      = "0",
  carrier_num       = "/ABC1234",
  tax_type          = "1",
  tax_rate          = 5,
  amt               = 205,
  tax_amt           = 10,
  total_amt         = 215,
  item_name         = "拿鐵咖啡|巧克力蛋糕",
  item_count        = "2|1",
  item_unit         = "杯|個",
  item_price        = "65|85",
  item_amt          = "130|85",
  print_flag        = "N",
  status            = "1",
)

Result: SUCCESS -- Invoice stored to phone barcode carrier /ABC1234, no paper copy printed.

"Query the invoice I just issued"

You: 幫我查一下訂單 ORDER20260404001 的發票資料

AI calls:

query_invoice(
  search_type       = "1",
  merchant_order_no = "ORDER20260404001",
  total_amt         = 105,
)

Result: SUCCESS -- Returns full invoice details including invoice number TE00000000, buyer info, tax breakdown (Amt: 100, TaxAmt: 5, TotalAmt: 105), item details, invoice status (1=issued), upload status, BarCode, and QR codes.

"I need to issue a refund for a returned item"

You: 客人退了一杯拿鐵 65 元，幫我對發票 TE00000000 開折讓

AI calls:

issue_allowance(
  invoice_no        = "TE00000000",
  merchant_order_no = "ORDER20260404001",
  item_name         = "拿鐵咖啡",
  item_count        = "1",
  item_unit         = "杯",
  item_price        = "65",
  item_amt          = "65",
  item_tax_amt      = "3",
  total_amt         = 68,
  status            = "1",
)

Result: SUCCESS -- Allowance issued against invoice TE00000000 for NT$68 (65 + 3 tax). The remaining invoice amount is updated accordingly.

"Void that invoice -- it was issued by mistake"

You: 發票 TE00000000 開錯了，幫我作廢，原因是誤開發票

AI calls:

void_invoice(
  invoice_number = "TE00000000",
  invalid_reason = "誤開發票",
)

Result: SUCCESS -- Invoice TE00000000 voided. The platform will notify the buyer and upload the void record to the tax authority.

Note: Invoices can only be voided before the 14th of the next odd month (e.g., invoices issued in March-April can be voided before May 14th).

"Create a scheduled invoice for next week"

You: 幫我建一張預約發票，預計 2026-04-10 開立，金額 1000 元含稅

AI calls:

issue_invoice(
  merchant_order_no  = "SCH20260404001",
  buyer_name         = "預約客戶",
  category           = "B2C",
  tax_type           = "1",
  tax_rate           = 5,
  amt                = 952,
  tax_amt            = 48,
  total_amt          = 1000,
  item_name          = "訂閱服務",
  item_count         = "1",
  item_unit          = "式",
  item_price         = "1000",
  item_amt           = "1000",
  print_flag         = "Y",
  status             = "3",
  create_status_time = "2026-04-10",
)

Result: SUCCESS -- Invoice data saved, scheduled to issue on 2026-04-10. If you need to issue it earlier, use trigger_invoice to trigger it immediately.

"Trigger that scheduled invoice now"

You: 預約發票 SCH20260404001 要提前開立，幫我觸發

AI calls:

trigger_invoice(
  invoice_trans_no  = "26040423034604894",
  merchant_order_no = "SCH20260404001",
  total_amt         = 1000,
)

Result: SUCCESS -- Scheduled invoice triggered and issued immediately. Invoice number and random code are returned.

Tools Reference

Error Codes Reference

Common ezPay API response status codes:

For the complete error code list, refer to the ezPay API documentation.

Architecture

stdio (JSON-RPC 2.0)
  -> mcp_server.py           Entry point, side-effect import triggers tool registration
    -> app.py                FastMCP("mcp-ezpay-einvoice") singleton
      -> tools/invoice_tools.py    7 @mcp.tool() decorated functions
        -> connectors/ezpay_client.py   Encrypted form POST connector
          -> auth/ezpay_crypto.py       AES-256-CBC encrypt + CheckCode verify
            -> config/settings.py       Endpoints, URL builder, env var config

mcp-ezpay-einvoice/
|-- app.py                          # FastMCP server singleton
|-- mcp_server.py                   # Entry point (stdio transport)
|-- config/settings.py              # API endpoints, URL builder, credentials
|-- connectors/ezpay_client.py      # Encrypted form POST connector
|-- auth/ezpay_crypto.py            # AES-256-CBC encryption, CheckCode
|-- tools/invoice_tools.py          # 7 MCP tools (invoice + allowance lifecycle)
|-- tests/test_all_tools.py         # E2E test runner
|-- scripts/auth/test_connection.py # Connection and credential validator
|-- .mcp.json                       # Claude Code auto-discovery config
`-- .env.example                    # Environment variable template

Contributing

See CONTRIBUTING.md for setup instructions and guidelines.

1. Fork the repository
2. Create a feature branch: git checkout -b feat/your-feature
3. Make changes and run tests
4. Submit a pull request

License

MIT License -- see LICENSE for details.

Part of the Asgard Ecosystem

This server is part of the Asgard AI Platform, connecting AI assistants to real-world services across e-commerce, finance, government data, and more. See the full Asgard AI Platform.