VLLM MCP Server

A Model Context Protocol (MCP) server that enables text models to call multimodal models. This server supports both OpenAI and Dashscope (Alibaba Cloud) multimodal models, allowing text-only models to process images and other media formats through standardized MCP tools.

GitHub Repository: https://github.com/StanleyChanH/vllm-mcp

Features

Multi-Provider Support: OpenAI GPT-4 Vision and Dashscope Qwen-VL models
Multiple Transport Options: STDIO, HTTP, and Server-Sent Events (SSE)
Flexible Deployment: Docker, Docker Compose, and local development
Easy Configuration: JSON configuration files and environment variables
Comprehensive Tooling: MCP tools for model interaction, validation, and provider management

Quick Start

Prerequisites

Python 3.11+
uv package manager
API keys for OpenAI and/or Dashscope (阿里云)

Installation & Setup

Clone the repository:

git clone https://github.com/StanleyChanH/vllm-mcp.git
cd vllm-mcp

Set up environment:

cp .env.example .env
# Edit .env with your API keys
nano .env  # or use your preferred editor

Configure API keys (in .env file):

# Dashscope (阿里云) - Required for basic functionality
DASHSCOPE_API_KEY=sk-your-dashscope-api-key

# OpenAI - Optional
OPENAI_API_KEY=sk-your-openai-api-key

Install dependencies:
```
uv sync
```
Verify setup:
```
uv run python test_simple.py
```

Running the Server

Start the server (STDIO transport - default):
```
./scripts/start.sh
```

Start with HTTP transport:

./scripts/start.sh --transport http --host 0.0.0.0 --port 8080

Development mode with hot reload:
```
./scripts/start-dev.sh
```

Testing & Verification

List available models:
```
uv run python examples/list_models.py
```
Run basic tests:
```
uv run python test_simple.py
```

Test MCP tools:

uv run python examples/client_example.py

Docker Deployment

Build and run with Docker Compose:

# Create .env file with your API keys
cp .env.example .env

# Start the service
docker-compose up -d

Build manually:

docker build -t vllm-mcp .
docker run -p 8080:8080 --env-file .env vllm-mcp

Configuration

Environment Variables

# OpenAI Configuration
OPENAI_API_KEY=your_openai_api_key
OPENAI_BASE_URL=https://api.openai.com/v1  # Optional
OPENAI_DEFAULT_MODEL=gpt-4o
OPENAI_SUPPORTED_MODELS=gpt-4o,gpt-4o-mini,gpt-4-turbo,gpt-4-vision-preview

# Dashscope Configuration
DASHSCOPE_API_KEY=your_dashscope_api_key
DASHSCOPE_DEFAULT_MODEL=qwen-vl-plus
DASHSCOPE_SUPPORTED_MODELS=qwen-vl-plus,qwen-vl-max,qwen-vl-chat,qwen2-vl-7b-instruct,qwen2-vl-72b-instruct

# Server Configuration (optional)
VLLM_MCP_HOST=localhost
VLLM_MCP_PORT=8080
VLLM_MCP_TRANSPORT=stdio
VLLM_MCP_LOG_LEVEL=INFO

Configuration File

Create a config.json file:

{
  "host": "localhost",
  "port": 8080,
  "transport": "stdio",
  "log_level": "INFO",
  "providers": [
    {
      "provider_type": "openai",
      "api_key": "${OPENAI_API_KEY}",
      "base_url": "${OPENAI_BASE_URL}",
      "default_model": "gpt-4o",
      "max_tokens": 4000,
      "temperature": 0.7
    },
    {
      "provider_type": "dashscope",
      "api_key": "${DASHSCOPE_API_KEY}",
      "default_model": "qwen-vl-plus",
      "max_tokens": 4000,
      "temperature": 0.7
    }
  ]
}

MCP Tools

The server provides the following MCP tools:

`generate_multimodal_response`

Generate responses from multimodal models.

Parameters:

model (string): Model name to use
prompt (string): Text prompt
image_urls (array, optional): List of image URLs
file_paths (array, optional): List of file paths
system_prompt (string, optional): System prompt
max_tokens (integer, optional): Maximum tokens to generate
temperature (number, optional): Generation temperature
provider (string, optional): Provider name (auto-detected if not specified)

Example:

result = await session.call_tool("generate_multimodal_response", {
    "model": "gpt-4o",
    "prompt": "Describe this image",
    "image_urls": ["https://example.com/image.jpg"],
    "max_tokens": 500
})

`list_available_providers`

List available model providers and their supported models.

Example:

result = await session.call_tool("list_available_providers", {})

`validate_multimodal_request`

Validate if a multimodal request is supported by the specified provider.

Parameters:

model (string): Model name to validate
image_count (integer, optional): Number of images
file_count (integer, optional): Number of files
provider (string, optional): Provider name

Supported Models

OpenAI

gpt-4o
gpt-4o-mini
gpt-4-turbo
gpt-4-vision-preview

Dashscope

qwen-vl-plus
qwen-vl-max
qwen-vl-chat
qwen2-vl-7b-instruct
qwen2-vl-72b-instruct

Model Selection

Using Environment Variables

You can configure default models and supported models through environment variables:

# OpenAI
OPENAI_DEFAULT_MODEL=gpt-4o
OPENAI_SUPPORTED_MODELS=gpt-4o,gpt-4o-mini,gpt-4-turbo

# Dashscope
DASHSCOPE_DEFAULT_MODEL=qwen-vl-plus
DASHSCOPE_SUPPORTED_MODELS=qwen-vl-plus,qwen-vl-max

Listing Available Models

Use the list_available_providers tool to see all available models:

result = await session.call_tool("list_available_providers", {})
print(result.content[0].text)

Model Selection Examples

# Use specific OpenAI model
result = await session.call_tool("generate_multimodal_response", {
    "model": "gpt-4o-mini",  # Specify exact model
    "prompt": "Analyze this image",
    "image_urls": ["https://example.com/image.jpg"]
})

# Use specific Dashscope model
result = await session.call_tool("generate_multimodal_response", {
    "model": "qwen-vl-max",  # Specify exact model
    "prompt": "Describe what you see",
    "image_urls": ["https://example.com/image.jpg"]
})

# Auto-detect provider based on model name
# OpenAI models (gpt-*) will use OpenAI provider
# Dashscope models (qwen-*) will use Dashscope provider

Model Configuration File

You can also configure models in config.json:

{
  "providers": [
    {
      "provider_type": "openai",
      "api_key": "${OPENAI_API_KEY}",
      "default_model": "gpt-4o-mini",
      "supported_models": ["gpt-4o-mini", "gpt-4-turbo"],
      "max_tokens": 4000,
      "temperature": 0.7
    },
    {
      "provider_type": "dashscope",
      "api_key": "${DASHSCOPE_API_KEY}",
      "default_model": "qwen-vl-max",
      "supported_models": ["qwen-vl-plus", "qwen-vl-max"],
      "max_tokens": 4000,
      "temperature": 0.7
    }
  ]
}

Client Integration

Python Client

import asyncio
from mcp.client.session import ClientSession
from mcp.client.stdio import StdioServerParameters, stdio_client

async def main():
    server_params = StdioServerParameters(
        command="uv",
        args=["run", "python", "-m", "vllm_mcp.server"],
        env={"PYTHONPATH": "src"}
    )

    async with stdio_client(server_params) as (read, write):
        async with ClientSession(read, write) as session:
            await session.initialize()

            # Generate multimodal response
            result = await session.call_tool("generate_multimodal_response", {
                "model": "gpt-4o",
                "prompt": "Analyze this image",
                "image_urls": ["https://example.com/image.jpg"]
            })

            print(result.content[0].text)

asyncio.run(main())

MCP Client Configuration

Add to your MCP client configuration:

{
  "mcpServers": {
    "vllm-mcp": {
      "command": "uv",
      "args": ["run", "python", "-m", "vllm_mcp.server"],
      "env": {
        "PYTHONPATH": "src",
        "OPENAI_API_KEY": "${OPENAI_API_KEY}",
        "DASHSCOPE_API_KEY": "${DASHSCOPE_API_KEY}"
      }
    }
  }
}

Development

Project Structure

vllm-mcp/
├── src/vllm_mcp/
│   ├── __init__.py
│   ├── server.py          # Main MCP server
│   ├── models.py          # Data models
│   └── providers/
│       ├── __init__.py
│       ├── openai_provider.py
│       └── dashscope_provider.py
├── scripts/
│   ├── start.sh           # Production startup
│   └── start-dev.sh       # Development startup
├── examples/
│   ├── client_example.py  # Example client
│   └── mcp_client_config.json
├── docker-compose.yml
├── Dockerfile
├── config.json
└── README.md

Adding New Providers

Create a new provider class in src/vllm_mcp/providers/
Implement the required methods:
- generate_response()
- is_model_supported()
- validate_request()
Register the provider in src/vllm_mcp/server.py
Update configuration schema

Running Tests

# Install development dependencies
uv add --dev pytest pytest-asyncio

# Run tests
uv run pytest

Deployment Options

STDIO Transport (Default)

Best for MCP client integrations and local development.

vllm-mcp --transport stdio

HTTP Transport

Suitable for web service deployments.

vllm-mcp --transport http --host 0.0.0.0 --port 8080

SSE Transport

For real-time streaming responses.

vllm-mcp --transport sse --host 0.0.0.0 --port 8080

Troubleshooting

Common Issues

Import Error: No module named 'vllm_mcp'

# Make sure you're in the project root and run:
uv sync
export PYTHONPATH="src:$PYTHONPATH"

API Key Not Found

# Ensure your .env file is properly configured:
cp .env.example .env
# Edit .env with your actual API keys

Dashscope API Errors
- Verify your API key is valid and active
- Check if you have sufficient quota
- Ensure network connectivity to Dashscope services

Server Startup Issues

# Check for port conflicts:
lsof -i :8080

# Try a different port:
./scripts/start.sh --port 8081

Docker Issues

# Rebuild Docker image:
docker-compose down
docker-compose build --no-cache
docker-compose up -d

Debug Mode

Enable debug logging for troubleshooting:

./scripts/start.sh --log-level DEBUG

Getting Help

Check SETUP_GUIDE.md for detailed setup instructions
Run uv run python test_simple.py to verify basic functionality
Review logs for error messages and warnings

License

MIT License

Contributing

Fork the repository
Create a feature branch
Make your changes
Add tests if applicable
Submit a pull request

Support

Issues: GitHub Issues
Documentation: Wiki