gNucleus Text-To-CAD

You can run the gNucleus Text-To-CAD MCP server locally to generate CAD parts or assemblies from natural language prompts. It connects to the gNucleus GenAI models and exposes a convenient MCP interface so clients can request CAD from text inputs and view results in a 3D viewer.

How to use

You interact with the server through an MCP client. Send prompts that end with in CAD to generate CAD parts or assemblies. The server returns a design specification that includes a Key Parameter, a Description, and a shared 3D viewer URL. The URL expires after 24 hours. If the output does not include a shared URL, you can prompt for it or use the viewer URL from a subsequent run.

How to install

Prerequisites you need before installing the MCP server are Python 3.7 or newer.

Create a Python virtual environment (recommended) and activate it.

python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate

Install the required Python packages from the provided requirements file.

pip install -r requirements.txt

Create a configuration file with your gNucleus host and API key. Use these values based on your account type.

GNUCLEUS_HOST="genai.gnucleus.ai"
GNUCLEUS_API_KEY=<your-personal-api-key>

If you are using an Enterprise account, include your organization ID.

GNUCLEUS_HOST="genai.gnucleus.ai"
GNUCLEUS_API_KEY=<your-team-key>
GNUCLEUS_ORG_ID=<your-team-id>

Run the server and test locally

Start the MCP server with Python.

python main.py

You can test the server using the inspector tool to verify MCP integration.

npx @modelcontextprotocol/inspector python3 main.py

Additional setup for Claude Desktop users

If you use Claude Desktop, configure an MCP server entry for either a virtual Python environment or a global Python environment.

Claude Desktop configuration for a virtual environment

{
  "mcpServers": {
    "gnucleus": {
      "command": "/ABSOLUTE/PATH/TO/YOUR/text-to-cad-mcp/.venv/bin/python",
      "args": [
        "/ABSOLUTE/PATH/TO/YOUR/text-to-cad-mcp/main.py"
      ],
      "workingDirectory": "/ABSOLUTE/PATH/TO/YOUR/text-to-cad-mcp",
      "env": {
        "GNUCLEUS_HOST": "genai.gnucleus.ai",
        "GNUCLEUS_API_KEY": "YOUR_API_KEY_HERE"
      }
    }
  }
}

Claude Desktop configuration for a global Python environment

{
  "mcpServers": {
    "gnucleus": {
      "command": "python",
      "args": [
        "/ABSOLUTE/PATH/TO/YOUR/text-to-cad-mcp/main.py"
      ],
      "workingDirectory": "/ABSOLUTE/PATH/TO/YOUR/text-to-cad-mcp",
      "env": {
        "GNUCLEUS_HOST": "genai.gnucleus.ai",
        "GNUCLEUS_API_KEY": "YOUR_API_KEY_HERE"
      }
    }
  }
}

Chat with Claude to generate CAD models

Open Claude Desktop and select the gNucleus Text-To-CAD tools. When you chat, append “in CAD” to prompts or tell Claude to use the text-to-cad tools so it triggers the MCP tool.”

Result presentation and sharing

The generated CAD design includes a Key Parameter and Description, plus a shared URL that opens the 3D viewer. The link expires after 24 hours. If the shared URL is not shown, ask Claude to include it in future outputs.

Downloading CAD models

Downloading CAD models from the viewer is not supported in this setup. To obtain the CAD file, log in to gNucleus and download the CAD file from the same prompt using the full feature set.

Troubleshooting

If the CAD model looks incorrect or only partially generated, log in to gNucleus, re-run the same prompt, and download the CAD file (e.g., FreeCAD format) to open it in your CAD software. Incomplete feature generation is a common cause.

If you encounter issues, report a bug or contact support with the model link and prompt at gNucleus contact page.

Security considerations

Keep your .env file secure and never commit it to version control. Run this server in a trusted and secure environment.

Available tools

text_to_cad

Generate CAD from input text using gNucleus GenAI models.