FreeCAD Robust MCP Server

An MCP (Model Context Protocol) server that enables integration between AI assistants (Claude, GPT, and other MCP-compatible tools) and FreeCAD, allowing AI-assisted development and debugging of 3D models, macros, and workbenches.

Table of Contents

• FreeCAD Robust MCP Server
  • Table of Contents
  • Features
  • Installation Requirements / Dependencies
  • For Users
    • Quick Links
  • Robust MCP Server
    • Installation
      • Using pip (recommended)
      • Using mise and just (from source)
      • Using Docker
    • Configuration
      • Environment Variables
      • Connection Modes
      • MCP Client Configuration
    • Usage
      • Starting the MCP Bridge in FreeCAD
        • Option A: Using the Workbench (Recommended)
        • Option B: Using just commands (from source)
      • Uninstalling the MCP Bridge
        • Checking for Legacy Components
        • Manual Cleanup (if needed)
      • Running Modes
        • XML-RPC Mode (Recommended)
        • Socket Mode (JSON-RPC)
        • Headless Mode
        • Embedded Mode (Linux Only)
    • Available Tools
      • Execution & Debugging (5 tools)
      • Document Management (7 tools)
      • Object Creation - Primitives (8 tools)
      • Object Management (12 tools)
      • PartDesign - Sketching (14 tools)
      • PartDesign - Patterns & Edges (5 tools)
      • View & Display (11 tools)
      • Undo/Redo (3 tools)
      • Export/Import (7 tools)
      • Macro Management (6 tools)
      • Parts Library (2 tools)
  • For Developers
  • Robust MCP Server Development
    • Prerequisites
    • Initial Setup
    • MCP Client Configuration (Development)
    • Development Workflow
    • Running FreeCAD with the MCP Bridge
      • GUI Mode (recommended for development)
      • Headless Mode (for automation/CI)
    • Running Tests
    • Code Quality
  • Architecture
  • Acknowledgements
    • Related Projects
  • License

The macros that were originally in this repo under the /macros directory have been permanently moved to two new GitHub repos:

• spkane/freecad-macro-cut-for-magnets
• spkane/freecad-macro-3d-print-multi-export

FreeCAD Forum: addon discussion post

Features

• 150+ MCP Tools: Comprehensive CAD operations including primitives, PartDesign, booleans, export
• Multiple Connection Modes: XML-RPC (recommended), JSON-RPC socket, or embedded
• GUI & Headless Support: Full modeling in headless mode, plus screenshots/colors in GUI mode
• Macro Development: Create, edit, run, and template FreeCAD macros via MCP

Installation Requirements / Dependencies

• FreeCAD 0.21+ or 1.0+
• Python 3.11 (required for FreeCAD ABI compatibility)

For Users

This section covers installation and usage for end users who want to use the Robust MCP Server with AI assistants.

Quick Links

| Resource | Description | | ------------------------------------------------------------------------------------- | --------------------------------------------- | | Documentation | Full documentation, guides, and API reference | | Docker Hub | Pre-built Docker images for easy deployment | | PyPI | Python package for pip installation | | GitHub Releases | Release archives and changelogs |

Robust MCP Server

Note: The Linux container and PyPI package are both named freecad-robust-mcp which differs slightly from this git repository name.

Installation

Using pip (recommended)

pip install freecad-robust-mcp

Using mise and just (from source)

git clone https://github.com/spkane/freecad-addon-robust-mcp-server.git
cd freecad-addon-robust-mcp-server

# Install mise via the Official mise installer script (if not already installed)
curl https://mise.run | sh

mise trust
mise install
just setup

Using Docker

Run the Robust MCP Server in a container. This is useful for isolated environments or when you don't want to install Python dependencies on your host.

# Pull from Docker Hub (when published)
docker pull spkane/freecad-robust-mcp

# Or build locally
git clone https://github.com/spkane/freecad-addon-robust-mcp-server.git
cd freecad-addon-robust-mcp-server
docker build -t freecad-robust-mcp .

# Or use just commands (if you have mise/just installed)
just docker::build        # Build for local architecture
just docker::build-multi  # Build multi-arch (amd64 + arm64)

Note: The containerized Robust MCP Server only supports xmlrpc and socket modes since FreeCAD runs on your host machine (not in the container). The container connects to FreeCAD via host.docker.internal.

Configuration

Environment Variables

| Variable | Description | Default | | --------------------- | ---------------------------------------------------- | ----------- | | FREECAD_MODE | Connection mode: xmlrpc, socket, or embedded | xmlrpc | | FREECAD_PATH | Path to FreeCAD's lib directory (embedded mode only) | Auto-detect | | FREECAD_SOCKET_HOST | Socket/XML-RPC server hostname | localhost | | FREECAD_SOCKET_PORT | JSON-RPC socket server port | 9876 | | FREECAD_XMLRPC_PORT | XML-RPC server port | 9875 | | FREECAD_TIMEOUT_MS | Execution timeout in ms | 30000 |

Connection Modes

| Mode | Description | Platform Support | | ---------- | ------------------------------------------- | --------------------------------- | | xmlrpc | Connects to FreeCAD via XML-RPC (port 9875) | All platforms (recommended) | | socket | Connects via JSON-RPC socket (port 9876) | All platforms | | embedded | Imports FreeCAD directly into process | Linux only (crashes on macOS) |

Note: Embedded mode crashes on macOS because FreeCAD's FreeCAD.so links to @rpath/libpython3.11.dylib, which conflicts with external Python interpreters. Use xmlrpc or socket mode on macOS and Windows.

MCP Client Configuration

Add something like the following to your MCP client settings. For Claude Code, this is ~/.claude/claude_desktop_config.json or a project .mcp.json file:

{
  "mc