lexoffice-mcp

MCP server (built with FastMCP) for creating invoices in Lexware Office (formerly lexoffice).

Tools

create_invoice supports one-time addresses or existing contacts, custom, service, material and text line items, net, gross and vat-free tax types, performance dates and periods, payment terms with early payment discount, and title, introduction and remark texts. It returns the invoice id, number, status, totals and deep links into Lexware.

The client respects the Lexware limit of 2 requests per second and retries 429 responses. Other errors are not retried, so a failing request never creates duplicate invoices.

Related MCP server: sevdesk MCP Server

Example

Ask Claude something like:

Create a draft invoice for Bike & Ride GmbH, Musterstraße 42, 79112 Freiburg, Germany: 8 hours of consulting at 120 EUR net with 19% VAT, payable within 14 days.

Claude calls create_invoice with a payload such as:

{
  "invoice": {
    "address": { "name": "Bike & Ride GmbH", "street": "Musterstraße 42", "zip": "79112", "city": "Freiburg", "country_code": "DE" },
    "line_items": [
      { "name": "Consulting", "quantity": 8, "unit_name": "Stunde", "unit_price": 120, "tax_rate_percentage": 19 }
    ],
    "payment_conditions": { "payment_term_label": "Zahlbar innerhalb von 14 Tagen", "payment_term_duration": 14 }
  }
}

and gets back the invoice number, totals and a link to open the draft in Lexware.

Setup

1. Create an API key at https://app.lexware.de/addons/public-api.

2. Clone this repository. No install step is needed: uv run --with resolves the dependencies (fastmcp, httpx) on the fly when the server starts.

Run the server manually to check it starts:

LEXWARE_API_KEY=your-api-key uv run --with "fastmcp>=4" --with httpx /absolute/path/to/lexoffice_mcp/main.py

Install into Claude Code

claude mcp add lexware --scope user \
  -e LEXWARE_API_KEY=your-api-key \
  -- uv run --with "fastmcp>=4" --with httpx /absolute/path/to/lexoffice_mcp/main.py

Check the connection with claude mcp list or /mcp inside Claude Code. The key is stored in plain text in your Claude Code configuration, so use a key dedicated to this integration and revoke it when no longer needed.

Install into Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "lexware": {
      "command": "uv",
      "args": ["run", "--with", "fastmcp>=4", "--with", "httpx", "/absolute/path/to/lexoffice_mcp/main.py"],
      "env": { "LEXWARE_API_KEY": "your-api-key" }
    }
  }
}

Configuration

Development

uv sync
uv run pytest

Tests run the server in memory against a mocked Lexware API, so no API key is needed.

License

MIT, see LICENSE.