MCP Server

Model Context Protocol server for AI assistants.

Generate invoices with natural language using Claude, GPT, or other AI tools.

Installation

npm install -g @thelawin/mcp-server

Or use npx:

npx @thelawin/mcp-server

Configuration

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "thelawin": {
      "command": "npx",
      "args": ["@thelawin/mcp-server"],
      "env": {
        "THELAWIN_API_KEY": "env_sandbox_xxx"
      }
    }
  }
}

Environment Variables

Variable	Required	Description
THELAWIN_API_KEY	Yes	Your thelawin.dev API key
THELAWIN_API_URL	No	Custom API URL

Available Tools

generate_invoice

Generate a ZUGFeRD-compliant invoice.

Parameters:

Name	Type	Description
number	string	Invoice number
date	string	Invoice date (YYYY-MM-DD)
seller_name	string	Seller company name
seller_vat_id	string	Seller VAT ID
seller_city	string	Seller city
seller_country	string	Seller country code
buyer_name	string	Buyer company name
buyer_city	string	Buyer city
buyer_country	string	Buyer country code
items	array	Line items
template	string	Template: minimal, classic, compact

Returns: PDF file path and validation status

validate_invoice

Validate an existing PDF for ZUGFeRD/Factur-X compliance.

Parameters:

Name	Type	Description
pdf_path	string	Path to PDF file

Returns: Validation result with errors/warnings

Example Usage

With Claude

Human: Generate an invoice for Acme GmbH (DE123456789) in Berlin
       to Customer AG in Munich. 8 hours of consulting at €150/hour.

Claude: I'll generate that invoice for you using thelawin.dev.

[Uses generate_invoice tool with the provided details]

I've generated the invoice. Here are the details:
- Invoice Number: 2026-001
- Total: €1,428.00 (including 19% VAT)
- Validation: ✓ EN16931 compliant
- Saved to: ./invoice-2026-001.pdf

Natural Language Examples

• "Create an invoice for my consulting work this month"
• "Generate a ZUGFeRD invoice for customer XYZ"
• "Make an invoice with 3 line items for the software project"
• "Validate this PDF to check if it's ZUGFeRD compliant"

Features

• Natural language interface - No need to remember API syntax
• Automatic validation - All invoices are EN16931 compliant
• File handling - PDFs saved automatically
• Error feedback - Clear error messages if something's wrong

Troubleshooting

"API key not found"

Ensure THELAWIN_API_KEY is set in your environment or MCP configuration.

"Connection refused"

Check that the MCP server is running and your Claude Desktop config is correct.

"Validation failed"

The AI will show you which fields are missing. Provide the required information.

Source Code

github.com/steviee/thelawin.dev/tree/main/mcp-server