mcp-einvoicing-be 🇧🇪

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Introduction

mcp-einvoicing-be is an MCP (Model Context Protocol) server that exposes tools for Belgian electronic invoicing. It covers the full Belgian e-invoicing ecosystem: Peppol BIS Billing 3.0, UBL 2.1, and the Mercurius network for public-sector invoicing. The server is part of the mcp-einvoicing-* family of country-specific servers, all built on top of mcp-einvoicing-core, which provides the shared validation engine, UBL abstractions, and Peppol network utilities.

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Installation

Requirements

• Python ≥ 3.11
• mcp-einvoicing-core (installed automatically as a dependency)

Using uv (recommended)

uv add mcp-einvoicing-be

Using pip

pip install mcp-einvoicing-be

From source

git clone https://github.com/cmendezs/mcp-einvoicing-be.git
cd mcp-einvoicing-be
uv sync --all-extras

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Configuration

Add the server to your MCP client configuration. For Claude Desktop, edit claude_desktop_config.json:

{
  "mcpServers": {
    "einvoicing-be": {
      "command": "uvx",
      "args": ["mcp-einvoicing-be"]
    }
  }
}

For a local development install:

{
  "mcpServers": {
    "einvoicing-be": {
      "command": "uv",
      "args": ["run", "mcp-einvoicing-be"],
      "cwd": "/path/to/mcp-einvoicing-be"
    }
  }
}

Environment variables

Variable	Description	Default
BCE_API_KEY	API key for the Belgian BCE/KBO enterprise database	—
PEPPOL_ENV	Peppol environment: production or test	production
PEPPOL_SML_URL	Override the SML lookup URL	(auto)
LOG_LEVEL	Logging level: DEBUG, INFO, WARNING, ERROR	INFO

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Available Tools

validate_invoice_be

Validates a UBL 2.1 XML invoice against Belgian business rules (EN 16931 + Peppol BIS 3.0 + Mercurius overlay).

Parameter	Type	Required	Description
xml	string	yes	Raw UBL 2.1 XML content
profile	string	no	peppol-bis-3 (default) or mercurius

Returns a ValidationResult with valid, errors, and warnings (each carrying the failed rule ID and a human-readable message).

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generate_invoice_be

Generates a valid UBL 2.1 Belgian e-invoice XML document from structured data.

Parameter	Type	Required	Description
invoice_data	object	yes	Invoice fields (see InvoiceInput schema below)
profile	string	no	peppol-bis-3 (default)

The InvoiceInput object supports:

{
  "invoice_number": "INV-2024-001",
  "issue_date": "2024-01-15",
  "due_date": "2024-02-14",
  "currency_code": "EUR",
  "supplier": { "name": "...", "vat_number": "BE0428759497", "address": {...} },
  "customer": { "name": "...", "vat_number": "BE0403170701", "address": {...} },
  "lines": [{ "description": "...", "quantity": 1, "unit_price": 100.00, "vat_rate": 21.0 }]
}

Returns a UBL 2.1 XML string.

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transform_to_ubl

Converts a structured JSON invoice payload to UBL 2.1 XML without full validation. Useful as a first step before validation.

Parameter	Type	Required	Description
data	object	yes	Source invoice data (same shape as InvoiceInput)

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lookup_vat_be

Looks up a Belgian enterprise number (VAT number) against the BCE/KBO public database.

Parameter	Type	Required	Description
vat_number	string	yes	Belgian VAT/enterprise number, e.g. BE0428759497 or 0123456789

Returns enterprise name, registered address, legal status, and NACE activity codes.

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check_peppol_participant_be

Checks whether a Belgian company is registered as a Peppol participant by querying the SMP/SML network.

Parameter	Type	Required	Description
identifier	string	yes	Peppol participant ID (e.g. 0088:BE0428759497) or plain Belgian VAT number

Returns registration status, supported document type identifiers, and the SMP access point endpoint URL.

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parse_ubl_invoice_be

Parses a UBL 2.1 XML invoice (Peppol BIS 3.0) into a structured dict. Satisfies the mandatory reception capability required by Art. 13quater of Royal Decree no. 1.

Parameter	Type	Required	Description
xml_content	string	yes	Raw UBL 2.1 XML invoice content

Returns {"success": true, "invoice": {...}, "warnings": []} on success, or {"success": false, "error": "..."} on parse failure.

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get_invoice_types_be

Returns the list of supported Belgian e-invoice document types (invoice, credit note, debit note) with their UBL customizationID and profileID values for each profile.

No input parameters required.

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B2G via Mercurius

Mercurius is the Belgian federal public-sector e-invoicing platform. It operates as a Peppol network receiver, not a separate API. B2G invoices are submitted through the standard Peppol network using the authority's participant ID in the 0208 scheme (KBO/BCE 10-digit enterprise number). The Access Point routes the invoice to Mercurius automatically. No Mercurius-specific submission endpoint or API key is required.

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Architecture

mcp-einvoicing-be/
├── src/
│   └── mcp_einvoicing_be/
│       ├── __init__.py
│       ├── server.py              # MCP server entry point & tool registration
│       ├── tools/
│       │   ├── __init__.py
│       │   ├── validation.py      # validate_invoice_be
│       │   ├── generation.py      # generate_invoice_be
│       │   ├── transformation.py  # transform_to_ubl
│       │   ├── parsing.py         # parse_ubl_invoice_be
│       │   └── lookup.py          # lookup_vat_be, check_peppol_participant_be, get_invoice_types_be
│       ├── models/
│       │   ├── __init__.py
│       │   ├── invoice.py         # InvoiceInput, InvoiceLine, ValidationResult
│       │   └── party.py           # Supplier, Customer, Address
│       ├── standards/
│       │   ├── __init__.py
│       │   ├── peppol_bis_3.py    # Peppol BIS Billing 3.0 rules & customization IDs
│       │   ├── ubl.py             # UBL 2.1 namespace constants & XML helpers
│       │   ├── pint_be.py         # PINT-BE placeholder (removed in v0.4.0)
│       │   └── mercurius.py       # Mercurius network config & overlay rules
│       └── utils/
│           ├── __init__.py
│           └── helpers.py         # VAT number normalization, date formatting, etc.
├── tests/
│   ├── __init__.py
│   ├── conftest.py
│   ├── test_tools/
│   │   ├── __init__.py
│   │   ├── test_validation.py
│   │   ├── test_generation.py
│   │   └── test_transformation.py
│   └── fixtures/
│       ├── invoice_valid_peppol.xml
│       ├── invoice_valid_pint_be.xml
│       └── invoice_invalid.xml
├── .github/
│   └── workflows/
│       ├── ci.yml
│       └── publish.yml
├── pyproject.toml
├── CHANGELOG.md
├── CONTRIBUTING.md
└── LICENSE

Relationship to mcp-einvoicing-core

mcp-einvoicing-core provides:

• Shared UBL 2.1/2.3 XML parsing and serialization utilities
• EN 16931 base validation rules (syntax + semantic)
• Peppol network client (SMP lookup, SML resolution)
• Common Pydantic base models (BaseInvoice, BaseParty, BaseValidationResult)

mcp-einvoicing-be adds Belgium-specific logic on top:

• Peppol BIS 3.0 business rule validation (XPath-based)
• Mercurius network overlay rules for B2G invoicing
• BCE/KBO enterprise database integration
• Belgian VAT number normalization (BTW/TVA format) and OGM/VCS check-digit validation
• UBL 2.1 invoice parsing for mandatory reception (Art. 13quater)
• customizationID and profileID values specific to the Belgian Peppol corner

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Contributing

Contributions are welcome. Please open an issue to discuss significant changes before submitting a pull request.

git clone https://github.com/cmendezs/mcp-einvoicing-be.git
cd mcp-einvoicing-be
uv sync --all-extras
uv run pytest
uv run ruff check src tests
uv run mypy src

All pull requests must:

• Pass the full test suite (pytest)
• Pass linting (ruff check)
• Pass type checking (mypy)
• Include or update tests for any changed behaviour
• Reference the relevant rule ID(s) when fixing a validation issue

See CONTRIBUTING.md for full guidelines.

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Other e-invoicing MCP servers

Country	Server
🌍 Global	mcp-einvoicing-core
🇧🇪 Belgium	mcp-einvoicing-be
🇧🇷 Brazil	mcp-nfe-br
🇫🇷 France	mcp-facture-electronique-fr
🇩🇪 Germany	mcp-einvoicing-de
🇮🇹 Italy	mcp-fattura-elettronica-it
🇵🇱 Poland	mcp-ksef-pl
🇪🇸 Spain	mcp-facturacion-electronica-es

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License

This project is licensed under the Apache 2.0 — see LICENSE for details.

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Changelog

See CHANGELOG.md for a full list of changes by version.