CLO3D MCP Server

Talk to CLO3D from Claude, Cursor, or any MCP client. Create patterns, swap fabrics, run simulations, export models. All from a chat window.

If you use CLO3D and you've wished you could script repetitive tasks without digging through the API docs, this is for you.

Your AI assistant  <-->  MCP Server  <-->  CLO3D Plugin  <-->  CLO3D

Quick Start

1. Load the plugin in CLO3D

One Python file, no dependencies.

1. Open CLO3D

2. Script > Script Editor

3. Open plugin/clo3d_mcp_plugin.py

4. Hit Run

You'll see [CLO MCP] Plugin started and [CLO MCP] Listening for commands in: ... in the console.

Run it once per CLO3D session. On Windows the plugin listens through a native timer driven by CLO3D's own event loop, so CLO3D stays fully usable. On other platforms it falls back to a blocking loop: the Script Editor stays busy while the plugin listens. Re-running the script replaces the previous listener.

2. Connect your AI client

Claude Code:

claude mcp add clo3d -- uvx --from git+https://github.com/Ubani-Studio/clo3d-mcp clo3d-mcp

Claude Desktop (add to claude_desktop_config.json):

{
  "mcpServers": {
    "clo3d": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/Ubani-Studio/clo3d-mcp", "clo3d-mcp"]
    }
  }
}

3. Go

Ask things like:

• "What patterns are in this project?"

• "Set the front bodice fabric to red"

• "Run 100 steps of simulation then export as GLB"

• "Export a turntable of all colorways"

Related MCP server: Blender MCP

What you get (46 tools)

Scene

Patterns

Fabrics

Export

Import

Simulation

Colorways

How it works

Two pieces:

The plugin (plugin/clo3d_mcp_plugin.py) runs inside CLO3D. It's a single Python file that polls a shared temp directory for JSON commands, calls the CLO3D Python API, and writes results back. No external dependencies, no sockets, works with CLO3D's built-in Python.

The MCP server (src/clo3d_mcp/) is a Python package that writes commands to that directory and reads responses. Any MCP-compatible client (Claude, Cursor, etc.) can use it.

┌─────────────────┐   file-based IPC  ┌──────────────────┐     CLO3D API     ┌────────┐
│   MCP Server    │ ◄──────────────► │   CLO3D Plugin    │ ◄──────────────► │ CLO3D  │
│   (clo3d-mcp)   │  %TEMP%/clo3d_mcp │  (Python script)  │                  │        │
└─────────────────┘                   └──────────────────┘                  └────────┘

Your own tools

Keep house tools (your blocks, your naming scheme, your grading rules) in your own folder, private if you like, and the server loads them beside the built-ins. No fork.

# my_tools/house.py
def register(ext):
    @ext.tool()
    def prefix_pieces(prefix: str) -> dict:
        """Prefix every pattern piece name."""
        pieces = ext.send("get_pattern_list")["patterns"]
        for p in pieces:
            ext.send("set_pattern_name", {"pattern_index": p["index"], "name": f"{prefix}-{p['name']}"})
        return {"renamed": len(pieces)}

Point the server at the folder:

claude mcp add clo3d -e CLO3D_MCP_EXTENSIONS=/path/to/my_tools -- uvx --from git+https://github.com/Ubani-Studio/clo3d-mcp clo3d-mcp

Several folders or files are separated by : (; on Windows). Files starting with _ are skipped, so helpers can sit beside the tools. ext.send uses the commands the plug-in already handles. A file that fails to load is named in the server's log and by the list_extensions tool, never skipped in silence, and an extension cannot replace a built-in tool.

Troubleshooting

"Cannot find CLO3D communication directory": Is CLO3D running? Did you run the plugin script?

Plugin errors: Check the Script Editor console in CLO3D for Python tracebacks.

Every call times out although the plugin says it started: CLO3D's embedded Python does not run background threads once a script returns. Make sure you run the current plugin, which does not rely on a background thread.

Simulation/export timeout: These can take a while. The default timeout is 180 seconds.

Custom comm directory: Set the CLO3D_MCP_DIR environment variable to override the default shared directory path.

Requirements

• CLO3D with Python scripting support

• Python 3.10+

• uv or pip

Testing

clo3d-mcp is tested by the people who use it, on the CLO3D versions they run. If you try it, working or not, file a Tested on report: your CLO3D version, OS, client and what happened. It takes two minutes, failures count as much as successes, and every tester is credited in the next release.

Questions, ideas and polls on what to build next live in Discussions.

Development

git clone https://github.com/Ubani-Studio/clo3d-mcp.git
cd clo3d-mcp

# Install dev dependencies
uv sync --dev

# Run tests (no CLO3D needed, uses a mock server)
uv run pytest tests/ -v

# Run the MCP server locally
uv run clo3d-mcp

License

MIT for the code authored here. See LICENSE.

This repository contains no CLO3D SDK material. The plugin uses only the Python API that ships inside CLO3D, so you need your own CLO3D licence and nothing else from CLO.