OpenSCAD MCP Server

A production-ready Model Context Protocol (MCP) server that provides OpenSCAD 3D rendering capabilities to AI assistants and LLM applications. Built with FastMCP for robust, scalable performance.

🎯 Zero-Installation Execution

Run directly from GitHub without any setup:

uv run --with git+https://github.com/quellant/openscad-mcp.git openscad-mcp

Perfect for MCP clients, CI/CD pipelines, and instant deployment scenarios!

🚀 Quick Start

Zero-Installation Execution with uv

No installation required! Run directly from GitHub:

# Run via script entry point (recommended)
uv run --with git+https://github.com/quellant/openscad-mcp.git openscad-mcp

# Or run as Python module
uv run --with git+https://github.com/quellant/openscad-mcp.git python -m openscad_mcp

Traditional Installation (Optional)

# Clone and run locally
git clone https://github.com/quellant/openscad-mcp.git
cd openscad-mcp
uv run openscad-mcp

Configure with Claude Desktop

Add to your Claude Desktop configuration (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):

Option 1: Direct from GitHub (Recommended)

{
  "mcpServers": {
    "openscad": {
      "command": "uv",
      "args": ["run", "--with", "git+https://github.com/quellant/openscad-mcp.git", "openscad-mcp"],
      "env": {
        "OPENSCAD_PATH": "/usr/bin/openscad"
      }
    }
  }
}

Option 2: Local Installation

{
  "mcpServers": {
    "openscad": {
      "command": "uv",
      "args": ["run", "openscad-mcp"],
      "cwd": "/path/to/openscad-mcp",
      "env": {
        "OPENSCAD_PATH": "/usr/bin/openscad"
      }
    }
  }
}

🔒 Security: --allowedTools Requirement

IMPORTANT: When using the OpenSCAD MCP server with Claude CLI or other MCP clients, you MUST explicitly grant permissions using the --allowedTools flag for security. This prevents unauthorized tool usage and ensures controlled access to server capabilities.

Required Permissions

The OpenSCAD MCP server requires explicit permission for each tool:

• openscad-mcp:check_openscad - Permission to check OpenSCAD installation
• openscad-mcp:render_single - Permission to render single views
• openscad-mcp:render_perspectives - Permission to render multiple perspectives

Example Usage with Claude CLI

# Start the server with uv and grant permissions
# (Create mcp-config.json with uv configuration first)

# Grant permission for a single tool
claude --config mcp-config.json \
       --allowedTools openscad-mcp:check_openscad \
       "Check if OpenSCAD is installed"

# Grant permission for multiple tools
claude --config mcp-config.json \
       --allowedTools openscad-mcp:check_openscad,openscad-mcp:render_single \
       "Render a cube with dimensions 30x30x30"

# Grant full permissions for all OpenSCAD tools
claude --config mcp-config.json \
       --allowedTools openscad-mcp:check_openscad,openscad-mcp:render_single,openscad-mcp:render_perspectives \
       "Create a gear model and show it from multiple angles"

Create mcp-config.json for Claude CLI:

{
  "mcpServers": {
    "openscad-mcp": {
      "command": "uv",
      "args": ["run", "--with", "git+https://github.com/quellant/openscad-mcp.git", "openscad-mcp"],
      "env": {
        "OPENSCAD_PATH": "/usr/bin/openscad"
      }
    }
  }
}

Testing with Permissions

Use the provided test script to verify proper permission configuration:

# Run all permission tests
./test_claude_with_permissions.sh all

# Test individual tools
./test_claude_with_permissions.sh check        # Test check_openscad only
./test_claude_with_permissions.sh single       # Test render_single only
./test_claude_with_permissions.sh perspectives # Test render_perspectives only

# Launch interactive session with full permissions
./test_claude_with_permissions.sh interactive

# Show usage examples
./test_claude_with_permissions.sh examples

✨ Features

• 🎯 Production-Ready: 100% test success rate with comprehensive integration testing
• 🔧 Single View Rendering: Render OpenSCAD models from any camera angle with full control
• 📐 Multiple Perspectives: Generate standard orthographic and isometric views automatically
• 🎬 Animation Support: Create turntable animations for 360° model visualization
• ⚡ Async Processing: Non-blocking renders using FastMCP framework for optimal performance
• 🖼️ Base64 Encoding: Images returned as base64-encoded PNGs for seamless integration
• ✅ Verified Compatibility: Fully compatible with FastMCP 2.11.3 and Pydantic 2.11.7

📋 Prerequisites

• Python 3.10+ (required for FastMCP 2.11.3)
• OpenSCAD (Download from openscad.org)
• uv (Install from docs.astral.sh) - Only needed for zero-installation execution

No additional Python packages required when using uv - all dependencies are handled automatically!

📦 Installation

Method 1: Zero-Installation with uv (Recommended)

No installation required! Just run directly:

# Run directly from GitHub - uv handles everything automatically
uv run --with git+https://github.com/quellant/openscad-mcp.git openscad-mcp

# All dependencies (FastMCP 2.11.3, Pydantic 2.11.7, etc.) are resolved and installed automatically

Method 2: Local Development with uv

# Clone for local development
git clone https://github.com/quellant/openscad-mcp.git
cd openscad-mcp

# Run with uv (installs dependencies automatically)
uv run openscad-mcp

# Or run as module
uv run python -m openscad_mcp

Method 3: Traditional pip Installation

# Only if you can't use uv
git clone https://github.com/quellant/openscad-mcp.git
cd openscad-mcp
pip install -e .
python -m openscad_mcp

⚙️ Configuration

Environment Variables

Create a .env file in the project root:

# OpenSCAD Configuration
OPENSCAD_PATH=/usr/bin/openscad  # Path to OpenSCAD executable
OPENSCAD_TIMEOUT=30               # Timeout for rendering operations (seconds)

# Server Configuration
MCP_SERVER_NAME=openscad-mcp
MCP_SERVER_VERSION=1.0.0
MCP_SERVER_TRANSPORT=stdio        # Transport: stdio, sse, or http

# Rendering Configuration
MCP_RENDER_MAX_CONCURRENT=4       # Max concurrent renders
MCP_RENDER_DEFAULT_WIDTH=800      # Default image width
MCP_RENDER_DEFAULT_HEIGHT=600     # Default image height

Configuration File (Optional)

Create config.yaml for advanced configuration:

server:
  name: "OpenSCAD MCP Server"
  version: "1.0.0"
  transport: stdio

openscad:
  timeout: 30
  default_color_scheme: "Cornfield"

rendering:
  max_concurrent: 4
  default_width: 800
  default_height: 600

🛠️ Available MCP Tools

1. render_single

Render a single view of an OpenSCAD model with complete camera control.

Parameters:

Parameter	Type	Required	Description
scad_content	string	No*	OpenSCAD code to render
scad_file	string	No*	Path to .scad file
camera_position	[x,y,z]	No	Camera position (default: [30,30,30])
camera_target	[x,y,z]	No	Look-at point (default: [0,0,0])
camera_up	[x,y,z]	No	Up vector (default: [0,0,1])
image_size	[w,h]	No	Image dimensions in pixels
color_scheme	string	No	OpenSCAD color scheme
variables	dict	No	Variables to pass to OpenSCAD
auto_center	bool	No	Auto-center the model

*Either scad_content or scad_file must be provided

Example Request:

{
  "tool": "render_single",
  "arguments": {
    "scad_content": "cube([10, 10, 10]);",
    "camera_position": [30, 30, 30],
    "image_size": [800, 600],
    "color_scheme": "Cornfield"
  }
}

Example Response:

{
  "success": true,
  "image": "data:image/png;base64,iVBORw0KGgo...",
  "metadata": {
    "width": 800,
    "height": 600,
    "render_time": 1.23
  }
}

2. render_perspectives

Generate multiple standard views of a model (front, back, left, right, top, bottom, isometric).

Parameters:

Parameter	Type	Required	Description
scad_content	string	No*	OpenSCAD code to render
scad_file	string	No*	Path to .scad file
distance	float	No	Camera distance from origin
image_size	[w,h]	No	Image dimensions for each view
variables	dict	No	Variables to pass to OpenSCAD
views	list	No	Specific views to render

Example Request:

{
  "tool": "render_perspectives",
  "arguments": {
    "scad_file": "model.scad",
    "views": ["front", "isometric", "top"],
    "distance": 200,
    "image_size": [400, 400]
  }
}

3. check_openscad

Verify OpenSCAD installation and get version information.

Parameters:

Parameter	Type	Required	Description
include_paths	bool	No	Include searched paths in response

Example Request:

{
  "tool": "check_openscad",
  "arguments": {
    "include_paths": true
  }
}

📚 MCP Resources

resource://server/info

Get server configuration and capabilities.

Returns:

• Server version and status
• OpenSCAD version and path
• Rendering capabilities
• Active operations count
• Configuration details

🏗️ Architecture

The server implements a clean architecture pattern:

┌─────────────────────────────────────┐
│         MCP Client (Claude)         │
└─────────────────────────────────────┘
                    │
                    ▼
┌─────────────────────────────────────┐
│    FastMCP Server (Presentation)    │
│        - MCP Protocol Handler       │
│        - Tool Decorators            │
└─────────────────────────────────────┘
                    │
                    ▼
┌─────────────────────────────────────┐
│     Application Layer (Business)    │
│        - Rendering Logic            │
│        - Parameter Validation       │
└─────────────────────────────────────┘
                    │
                    ▼
┌─────────────────────────────────────┐
│   Infrastructure Layer (External)   │
│        - OpenSCAD CLI               │
│        - File I/O Operations        │
└─────────────────────────────────────┘

🧪 Testing

The server has achieved 100% test success rate across all integration tests:

# Run comprehensive test suite
python comprehensive_test.py

# Run MCP tools integration test
python test_mcp_tools.py

# Run server startup test
python test_server_startup.py

See Test Report for detailed results.

🔧 Development

Project Structure

openscad-mcp-server/
├── src/
│   └── openscad_mcp/
│       ├── __init__.py         # Package initialization
│       ├── __main__.py          # Entry point
│       ├── server.py            # FastMCP server implementation
│       ├── types.py             # Pydantic models & types
│       └── utils/
│           └── config.py        # Configuration management
├── tests/                       # Test suite
├── pyproject.toml              # Project configuration
├── README.md                   # This file
├── CHANGELOG.md               # Version history
├── API.md                     # Detailed API documentation
└── .env.example               # Environment template

Extending the Server

To add new rendering capabilities:

1. Define parameter types in types.py:

class CustomRenderParams(BaseModel):
    # Your parameters here
    pass

2. Add tool function in server.py:

@mcp.tool
async def custom_render(params: CustomRenderParams) -> RenderResult:
    """Your custom rendering logic"""
    # Implementation
    pass

3. Update documentation in API.md

🐛 Troubleshooting

OpenSCAD Not Found

# Check OpenSCAD installation
which openscad

# Set environment variable
export OPENSCAD_PATH=/path/to/openscad

# Or add to .env file
OPENSCAD_PATH=/usr/local/bin/openscad

Permission Errors

# Ensure execute permissions
chmod +x /path/to/openscad

Rendering Timeouts

Increase timeout in configuration:

export OPENSCAD_TIMEOUT=60  # 60 seconds

FastMCP Compatibility Issues

Ensure correct versions:

pip install fastmcp==2.11.3 pydantic==2.11.7

📈 Performance

• Single view rendering: ~1-3 seconds (complexity dependent)
• Multiple perspectives: ~5-10 seconds for 8 views
• Base64 encoding: < 0.1s overhead
• Memory footprint: ~50 MB base + 10-20 MB per render
• Concurrent renders: Up to 4 (configurable)

🚦 Production Status

✅ Ready for Production

• All tests passing (100% success rate)
• FastMCP 2.11.3 compatibility verified
• Comprehensive error handling
• Async operation support
• Resource management implemented
• Documentation complete

📝 License

MIT License - See LICENSE file for details

🤝 Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

📮 Support

• Issues: GitHub Issues
• Documentation: Full API Documentation
• Test Report: Integration Test Results

🙏 Acknowledgments

• FastMCP - The excellent MCP framework
• OpenSCAD - The programmable CAD software
• Model Context Protocol - The MCP specification

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Version: 1.0.0 | Status: Production Ready | Last Updated: 2025-08-25