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VLLM MCP Server

by StanleyChanH

VLLM MCP Server

MIT License Python 3.11+ uv

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

  1. Clone the repository:

    git clone https://github.com/StanleyChanH/vllm-mcp.git cd vllm-mcp
  2. Set up environment:

    cp .env.example .env # Edit .env with your API keys nano .env # or use your preferred editor
  3. 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
  4. Install dependencies:

    uv sync
  5. Verify setup:

    uv run python test_simple.py

Running the Server

  1. Start the server (STDIO transport - default):

    ./scripts/start.sh
  2. Start with HTTP transport:

    ./scripts/start.sh --transport http --host 0.0.0.0 --port 8080
  3. Development mode with hot reload:

    ./scripts/start-dev.sh

Testing & Verification

  1. List available models:

    uv run python examples/list_models.py
  2. Run basic tests:

    uv run python test_simple.py
  3. Test MCP tools:

    uv run python examples/client_example.py

Docker Deployment

  1. Build and run with Docker Compose:

    # Create .env file with your API keys cp .env.example .env # Start the service docker-compose up -d
  2. 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

  1. Create a new provider class in src/vllm_mcp/providers/

  2. Implement the required methods:

    • generate_response()

    • is_model_supported()

    • validate_request()

  3. Register the provider in src/vllm_mcp/server.py

  4. 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

  1. Import Error: No module named 'vllm_mcp'

    # Make sure you're in the project root and run: uv sync export PYTHONPATH="src:$PYTHONPATH"
  2. API Key Not Found

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

    • Verify your API key is valid and active

    • Check if you have sufficient quota

    • Ensure network connectivity to Dashscope services

  4. Server Startup Issues

    # Check for port conflicts: lsof -i :8080 # Try a different port: ./scripts/start.sh --port 8081
  5. 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

  1. Fork the repository

  2. Create a feature branch

  3. Make your changes

  4. Add tests if applicable

  5. Submit a pull request

Support

Acknowledgments

-
security - not tested
A
license - permissive license
-
quality - not tested

remote-capable server

The server can be hosted and run remotely because it primarily relies on remote services or has no dependency on the local environment.

Enables text-only models to process images and other media formats by providing access to multimodal models from OpenAI and Dashscope (Alibaba Cloud). Supports flexible deployment options and comprehensive tooling for multimodal AI interactions.

  1. Features
    1. Quick Start
      1. Prerequisites
      2. Installation & Setup
      3. Running the Server
      4. Testing & Verification
      5. Docker Deployment
    2. Configuration
      1. Environment Variables
      2. Configuration File
    3. MCP Tools
      1. generate_multimodal_response
      2. list_available_providers
      3. validate_multimodal_request
    4. Supported Models
      1. OpenAI
      2. Dashscope
    5. Model Selection
      1. Using Environment Variables
      2. Listing Available Models
      3. Model Selection Examples
      4. Model Configuration File
    6. Client Integration
      1. Python Client
      2. MCP Client Configuration
    7. Development
      1. Project Structure
      2. Adding New Providers
      3. Running Tests
    8. Deployment Options
      1. STDIO Transport (Default)
      2. HTTP Transport
      3. SSE Transport
    9. Troubleshooting
      1. Common Issues
      2. Debug Mode
      3. Getting Help
    10. License
      1. Contributing
        1. Support
          1. Acknowledgments

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