xCOMET MCP Server
About
Translation quality evaluation using xCOMET models. Provides quality scoring (0-1), error detection with severity levels, and optimized batch processing with 25x speedup.
Explore
- Quality scoring on a 0–1 scale
- Error detection with minor, major, and critical severity levels
- Batch evaluation of up to 500 translation pairs
- GPU support for accelerated inference
- Persistent model loading for up to 177x speedup on consecutive requests
- Designed to integrate with other MCP servers like DeepL
Setting up with Highlight
This MCP is not yet compatible with Highlight’s one-click setup. However, you can still use it with Highlight by following these steps:
- Download and install Highlight from highlightai.com/download
- Navigate to the plugins tab and select "Add Custom Plugin"
-
Configure the plugin with the settings below
Plugin Name
xCOMET MCP ServerCommand (node, npx, python, etc.)Please refer to the README for specific instructions on how to obtain API keys or other required environment variables.
- Enable "Start Automatically" if you want the plugin to start when Highlight launches
From the repository
xCOMET requires Python with the following packages:
``bash
pip install "unbabel-comet>=2.2.0" fastapi uvicorn
bash
npm install
If you prefer a local installation:
`bash`
npm install -g xcomet-mcp-server
`
Then configure:
json
{
"mcpServers": {
"xcomet": {
"command": "xcomet-mcp-server"
}
}
}
TRANSPORT
| Variable | Default | Description |
|----------|---------|-------------|
| | stdio | Transport mode: stdio or http |PORT
| | 3000 | HTTP server port (when TRANSPORT=http) |XCOMET_MODEL
| | Unbabel/XCOMET-XL | xCOMET model to use |XCOMET_PYTHON_PATH
| | (auto-detect) | Python executable path (see below) |XCOMET_PRELOAD
| | false | Pre-load model at startup (v0.3.1+) |XCOMET_DEBUG
| | false | Enable verbose debug logging (v0.3.1+) |
pip install "unbabel-comet>=2.2.0" fastapi uvicorn
pip install torch --index-url https://download.pytorch.org/whl/cu118
Cause: XCOMET-XL requires ~8-10GB RAM.
Solutions:
1. Use the persistent server (v0.3.0+): Model loads once and stays in memory, avoiding repeated memory spikes
2. Use a lighter model: Set XCOMET_MODEL=Unbabel/wmt22-comet-da for lower memory usage (~3GB)``bash
3. Reduce batch size: For large batches, process in smaller chunks (100-200 pairs)
4. Close other applications: Free up RAM before running large evaluations
If you encounter issues:
1. Check the GitHub Issues
2. Enable debug logging by checking Claude Desktop's Developer Mode logs
3. Open a new issue with:
- Your OS and Python version
- The error message
- Your configuration (without sensitive data)
Claude Desktop / Cursor
Paste into your MCP client config file to install this server.
{
"mcpServers": {
"xcomet mcp server": {
"xcomet": {
"command": "npx",
"args": [
"-y",
"xcomet-mcp-server"
]
}
}
}
}
McpServers
{
"xcomet": {
"command": "npx",
"args": [
"-y",
"xcomet-mcp-server"
]
}
}
🎯 Overview
xCOMET MCP Server provides AI agents with the ability to evaluate machine translation quality. It integrates with the xCOMET model from Unbabel to provide: - Quality Scoring: Scores between 0-1 indicating translation quality - Error Detection: Identifies error spans with severity levels (minor/major/critical) - Batch Processing: Evaluate multiple translation pairs efficiently (optimized single model load) - GPU Support: Optional GPU acceleration for faster inference ``mermaid
graph LR
A[AI Agent] --> B[Node.js MCP Server]
B --> C[Python FastAPI Server]
C --> D[xCOMET Model<br/>Persistent in Memory]
D --> C
C --> B
B --> A
style D fill:#9f9
`
🔧 Prerequisites
Python Environment
xCOMET requires Python with the following packages:
`bash
pip install "unbabel-comet>=2.2.0" fastapi uvicorn
`
Model Download
The first run will download the xCOMET model (~14GB for XL, ~42GB for XXL):
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