GOLEM-3DMCP

"Shaped from clay, brought to life by words"

The most powerful MCP server for Rhinoceros 3D — 105 tools giving AI full read/write access to Rhino 8.

GOLEM-3DMCP implements the Model Context Protocol to give AI agents direct, programmatic control of Rhino 8 — create geometry, run booleans, drive Grasshopper, capture viewports, and execute arbitrary Python scripts, all through natural language.

Works with Claude Code, Cursor, Windsurf, and any MCP-compatible host.

Demo — A City Built Entirely by AI

An entire city generated in Rhino 8 through GOLEM-3DMCP — roads, skyscrapers, houses, trees, people, vehicles, a stadium, bridge, ferris wheel, harbor, wind turbines, and a floating GOLEM hologram. All created by Claude Code using natural language commands.

Watch the full demo on YouTube

Full city overview — ground, roads, buildings, park, harbor, sky

Skyline view — skyscrapers, bridge, wind turbines, floating GOLEM hologram

Close-up — GOLEM monument plaza, residential buildings, fountain

Street level — vehicles, people, street lamps, stadium, harbor with boats

Install

pip install golem-3dmcp

That's it. Three commands to go from zero to AI-powered Rhino:

# 1. Install
pip install golem-3dmcp

# 2. Deploy the Rhino plugin (one-time)
golem install-rhino

# 3. Verify everything works
golem doctor

Connect to Your AI Agent

Add to your MCP configuration (Claude Code, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "golem-3dmcp": {
      "command": "uvx",
      "args": ["golem-3dmcp"]
    }
  }
}

Start talking to Rhino through AI.

105 Tools Across 9 Categories

See Tool Reference for the complete API with parameters and examples.

Architecture

 AI Agent (Claude Code / Cursor / Windsurf)
      |
      |  MCP (stdio, JSON-RPC)
      v
+---------------------------+
|     GOLEM MCP Server      |
|     Python 3.10+          |
|     FastMCP + 9 tool      |
|     modules               |
+---------------------------+
      |
      |  TCP 127.0.0.1:9876
      |  Length-prefixed JSON
      v
+---------------------------+
|     Rhino Plugin          |
|     Python 3.9 (embedded) |
|     TCP Server            |
|     9 handler modules     |
+---------------------------+
      |
      |  RhinoCommon + rhinoscriptsyntax
      v
+---------------------------+       +-------------------------+
|     Rhinoceros 3D         | <---> |   Grasshopper           |
|     Document, Geometry,   |       |   Sub-server :9877      |
|     Layers, Views         |       |   Definitions, Params   |
+---------------------------+       +-------------------------+

Quick Start Examples

Create and combine geometry:

Create a 100 x 50 x 30 box on a layer called 'Structure',
then boolean-union it with a sphere of radius 20 centred at [50, 25, 30].

Query the scene:

List all objects on the 'Walls' layer and tell me their volumes.

Drive Grasshopper:

Open parametric_facade.gh, set the 'PanelCount' slider to 24,
recompute, and bake the result to a 'Facade' layer.

Capture a viewport:

Set perspective view to shaded mode, zoom to extents, and capture a screenshot.

Execute arbitrary Python:

import Rhino.Geometry as rg
pts = [rg.Point3d(i*10, 0, i**2) for i in range(20)]
crv = rg.Curve.CreateInterpolatedCurve(pts, 3)
sc.doc.Objects.AddCurve(crv)
__result__ = {"point_count": len(pts), "length": crv.GetLength()}

Loading the Rhino Plugin

1. Open Rhino 8
2. Open Script Editor: Tools > Python Script > Edit
3. Open startup.py (deployed by golem install-rhino) and click Run

GOLEM-3DMCP: Starting server on 127.0.0.1:9876...
GOLEM-3DMCP: Server started successfully!
GOLEM-3DMCP: 135 handler methods registered.

Auto-start on every Rhino launch: Tools > Options > RhinoScript > Startup Scripts > Add startup.py

Configuration

Requirements

The Rhino plugin runs inside Rhino's embedded Python 3.9 with zero external dependencies.

Troubleshooting

Run golem doctor to diagnose issues automatically.

See Troubleshooting Guide for detailed solutions.

Documentation

• Architecture — System design, threading model, data flow
• Tool Reference — All 105 tools with parameters and examples
• Protocol Specification — TCP wire format, message framing, error codes
• Troubleshooting — Common issues and solutions

Testing

# Unit tests (no Rhino needed)
pytest tests/ -v --ignore=tests/test_integration.py

# Full suite (integration tests auto-skip if Rhino not running)
pytest tests/ -v

# Integration tests only (requires Rhino + plugin running)
pytest tests/test_integration.py -v -m integration

Branch Strategy

This repository uses two branches:

• Develop on main — all tool modules, Rhino plugin, tests, and documentation live here.
• Release from the PyPI branch — packaging structure (pyproject.toml, src/ layout, publish scripts) is managed separately so releases don't pollute the development history.

main                          ← development
  └── claude/pypi-package-setup-PMCI5  ← PyPI releases (pip install golem-3dmcp)

Project Structure

golem-3dmcp/
├── src/golem_3dmcp/           # MCP Server (pip install golem-3dmcp)
│   ├── cli.py                 #   CLI entry point (golem command)
│   ├── server.py              #   FastMCP server
│   ├── connection.py          #   TCP client (singleton, thread-safe)
│   ├── protocol.py            #   Wire format: 4-byte length prefix + JSON
│   ├── config.py              #   Environment variable configuration
│   ├── models/                #   Pydantic data models
│   ├── tools/                 #   9 MCP tool modules
│   └── _rhino_plugin/         #   Bundled Rhino plugin (deployed via CLI)
├── tests/                     # 226 tests (pytest)
├── docs/                      # Architecture, protocol spec, tool reference
└── pyproject.toml             # Package definition

License

MIT License. See LICENSE for details.

Credits

Created by King Hippopotamus
Built by NEXUS AI — 195 autonomous agents | 20 departments | 11 tiers

Built with: FastMCP · RhinoCommon · rhinoscriptsyntax · Grasshopper SDK

"From formless clay, through the power of words, form emerges."