AWS S3 Upload MCP Server

A high-performance MCP (Model Context Protocol) server for uploading images to AWS S3, specifically designed for Figma → MCP → HTML workflows.

🎯 Features

• FastMCP Framework: Built with the high-performance Pythonic MCP library
• Image Processing: Automatic optimization, WebP conversion, and compression
• Batch Upload: Parallel processing for multiple images
• AWS S3 Integration: Secure upload with proper IAM permissions
• Type Safety: Full Pydantic model validation
• Async Support: Non-blocking operations with asyncio

🚀 Quick Start

Prerequisites

• Python 3.10+
• AWS Account with S3 access
• uv package manager (recommended)

Installation

# Clone the repository
git clone https://github.com/aucus/s3-upload-mcp-server.git
cd s3-upload-mcp-server

# Install with uv (recommended)
uv sync

# Or install with pip
pip install -e .

Environment Setup

Create a .env file in the project root:

# Copy env.example to .env and update with your values
cp env.example .env

# Edit .env with your AWS credentials
AWS_ACCESS_KEY_ID=your_access_key
AWS_SECRET_ACCESS_KEY=your_secret_key
AWS_REGION=ap-northeast-2
S3_BUCKET_NAME=your-bucket-name

Running the Server

# STDIO transport (for Claude Desktop)
uv run fastmcp run src/server.py

# HTTP transport (for web clients)
uv run python -m src.server -- --transport http --port 8000

🛠️ MCP Tools

upload_image_to_s3

Upload a single image file to S3 and return a public URL.

Parameters:

• file_path (str): Path to the image file
• bucket_name (str): S3 bucket name
• key (str, optional): S3 object key (auto-generated if not provided)
• optimize (bool): Enable image optimization (default: True)
• quality (int): Compression quality 1-100 (default: 80)

Returns:

• success (bool): Upload success status
• url (str): Public URL of uploaded image
• error (str): Error message if failed
• metadata (dict): Upload metadata

batch_upload_images

Upload multiple images in parallel to S3.

Parameters:

• file_paths (List[str]): List of image file paths
• bucket_name (str): S3 bucket name
• folder_prefix (str, optional): S3 folder prefix
• optimize (bool): Enable image optimization (default: True)

Returns:

• success (bool): Overall success status
• urls (List[str]): List of public URLs
• errors (List[str]): List of error messages
• total_files (int): Total number of files
• successful_uploads (int): Number of successful uploads

list_s3_buckets

List all accessible S3 buckets.

Returns:

• success (bool): Operation success status
• buckets (List[str]): List of bucket names
• error (str): Error message if failed

🔧 Claude Desktop Integration

Add to your Claude Desktop configuration:

{
  "mcpServers": {
    "s3-upload": {
      "command": "uv",
      "args": ["run", "s3-upload-mcp-server"],
      "env": {
        "AWS_REGION": "ap-northeast-2",
        "S3_BUCKET_NAME": "figma-assets-bucket"
      }
    }
  }
}

🧪 Testing

# Run all tests
uv run pytest

# Run with coverage
uv run pytest --cov=src --cov-report=html

# Run specific test file
uv run pytest tests/test_tools.py

📊 Performance

• Upload Speed: < 3 seconds for 1MB images
• Parallel Processing: Up to 5 files simultaneously
• Memory Usage: < 100MB
• CPU Usage: < 50% single core

🔒 Security

• Environment variable authentication
• IAM role support for EC2/Lambda
• HTTPS/TLS 1.2+ encryption
• S3 server-side encryption
• Least privilege access

📝 License

MIT License - see LICENSE file for details.

🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests
5. Submit a pull request

📞 Support

For issues and questions, please open an issue on GitHub.