rhino-mcp

A Model Context Protocol (MCP) server that enables interaction with Rhinoceros 3D software through Python scripts. This server allows you to execute RhinoPython scripts programmatically via the MCP protocol.

What This Project Does

This MCP server provides a bridge between MCP-compatible clients (like AI assistants) and Rhinoceros 3D. It allows you to:

• Execute Python scripts that interact with Rhino 3D
• Automate Rhino operations through the MCP protocol
• Control Rhino programmatically from external applications

The server creates a COM connection to Rhino using the winax library, executes Python scripts in Rhino's Python environment, and manages temporary script files.

Dependencies

Runtime Dependencies

• @modelcontextprotocol/sdk (^1.13.2): The Model Context Protocol SDK for building MCP servers. Provides the server infrastructure, tool registration, and stdio transport.
• winax (^3.6.2): A Node.js library for creating and interacting with Windows COM objects. Used to connect to Rhino's COM interface.

Development Dependencies

• typescript (^5.8.3): TypeScript compiler for type-safe JavaScript development
• @types/node (^24.0.8): TypeScript type definitions for Node.js

How It Works

1. Server Initialization: The server starts as an MCP server named "rhino-server" using stdio transport for communication.

2. Rhino Connection: When a tool is called, the server attempts to connect to Rhino via COM:

   • Creates a Rhino.Application COM object using winax
   • Sets Rhino to visible mode
   • Maintains a singleton instance that is reused across requests

3. Script Execution:

   • Receives Python script content via the rhino_execute tool
   • Creates a temporary script file in the temp-scripts directory
   • Executes the script in Rhino using the -_RunPythonScript command
   • Cleans up the temporary file after execution

4. Tool Registration: The server registers one tool:

   • rhino_execute: Executes a Python script in Rhino and returns the result

Prerequisites

• Node.js: Required to run the server (version compatible with ES2022 modules)
• Rhinoceros 3D: Must be installed on your Windows system
• Windows OS: Required for COM object support (winax only works on Windows)

Installation

1. Install dependencies:

npm install

2. Build the TypeScript code:

npm run build

Running the Server

Development Mode

Run the server directly with TypeScript (requires tsx):

npm run dev

Production Mode

Build first, then run:

npm run build
npm start

As a Binary

After building, the server can be run as:

node dist/index.js

Usage with MCP Clients

To use this server with an MCP client (like Claude Desktop or other MCP-compatible applications), you need to configure the client to connect to this server via stdio.

Example configuration for Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "rhino-mcp": {
      "command": "node",
      "args": ["path/to/rhino-mcp/dist/index.js"]
    }
  }
}

Available Tools

rhino_execute

Executes a Python script in Rhino 3D.

Input Schema:

• pythonScript (string): The Python script to execute in Rhino

Example Usage:

import rhinoscriptsyntax as rs

# Create a point at origin
point = rs.AddPoint([0, 0, 0])
print(f"Created point: {point}")

Project Structure

rhino-mcp/
├── src/
│   └── index.ts          # Main server implementation
├── dist/                  # Compiled JavaScript output
├── temp-scripts/          # Temporary Python script storage
├── package.json           # Project dependencies and scripts
├── tsconfig.json          # TypeScript configuration
└── README.md              # This file

Scripts

• npm run build: Compiles TypeScript to JavaScript in the dist directory
• npm run build:watch: Watches for changes and rebuilds automatically
• npm run dev: Runs the server in development mode using tsx
• npm start: Runs the compiled server from dist/index.js
• npm test: Placeholder test script (currently not implemented)

Notes

• The server requires Rhino to be installed and accessible via COM
• Scripts are temporarily stored in temp-scripts/ and cleaned up after execution
• The server maintains a single Rhino instance connection that is reused
• If the Rhino connection is lost, the server will attempt to reconnect on the next request
• This server is Windows-only due to COM object requirements