S3 MCP Server

An Amazon S3 Model Context Protocol (MCP) server that provides tools for interacting with S3 buckets and objects.

https://github.com/user-attachments/assets/d05ff0f1-e2bf-43b9-8d0c-82605abfb666

Features

🚀 MCP Transport Support

• ✅ STDIO Transport - Direct process communication for Claude Desktop

• ✅ HTTP Transport - REST API with Server-Sent Events for web clients

• ✅ Streamable HTTP - Real-time streaming for responsive interactions

🛠️ Available Tools

• ✅ list-buckets - List accessible S3 buckets with filtering

• ✅ list-objects - Browse objects within buckets with prefix filtering

• ✅ get-object - Retrieve object contents (text/binary support)

🐳 Deployment Options

• ✅ Local Node.js - Direct execution with npm/node

• ✅ Docker CLI - Containerized deployment with custom configuration

• ✅ Docker Compose - Full stack with MinIO for local testing

• ✅ MCP Inspector - Built-in debugging and testing interface

Related MCP server: AWS MCP Server

Overview

This MCP server allows Large Language Models (LLMs) like Claude to interact with AWS S3 storage. It provides tools for:

• Listing available S3 buckets

• Listing objects within a bucket

• Retrieving object contents

The server is built using TypeScript and the MCP SDK, providing a secure and standardized way for LLMs to interface with S3.

Installation

Prerequisites

• Node.js 18 or higher

• npm or yarn

• AWS credentials configured (either through environment variables or AWS credentials file)

• Docker (optional, for containerized setup)

Setup

1. Install via npm:

2. If building from source:

3. Configure AWS credentials and S3 access:

Create a .env file with your AWS configuration:

Or set these as environment variables.

Configuration

The server can be configured using the following environment variables:

Running the Server

Direct Node.js Execution

The server runs with HTTP transport by default, making it easy to test and debug:

When running with HTTP transport (default), the server will start on port 3000 and provide:

• Health check endpoint: http://localhost:3000/health

• MCP endpoint: http://localhost:3000/mcp

• SSE endpoint: http://localhost:3000/sse

Docker Setup 🐳

You can run the S3 MCP server as a Docker container using either Docker CLI or Docker Compose.

Using Docker CLI

1. Build the Docker image:

2. Run the container with environment variables:

3. Check container logs:

4. Stop and remove the container:

Note: For HTTP transport (default), add -p 3000:3000 to expose the HTTP port. For STDIO transport (Claude Desktop), no port mapping is needed as it uses Docker exec for direct communication.

Using Docker Compose

1. Build and start the Docker container:

2. To stop the container:

Using Docker with MinIO for Testing

The Docker Compose setup includes a MinIO service for local testing:

The MinIO service automatically creates two test buckets (test-bucket-1 and test-bucket-2) and uploads sample files for testing.

Debugging with MCP Inspector 🔍

The run-inspector.sh script provides an easy way to test and debug the S3 MCP server using the MCP Inspector. It supports multiple transport types and deployment modes.

Quick Start

Transport Types

The server supports two transport protocols:

HTTP Transport

• Best for: Web-based debugging, external client connections

• Provides: REST API endpoints, Server-Sent Events (SSE)

• Ports: 3000 (HTTP), 3001+ (Inspector UI)

STDIO Transport

• Best for: Direct process communication, Claude Desktop integration

• Provides: Standard input/output communication

• Ports: None (direct process communication)

Usage Examples

1. Local Development (HTTP)

This will:

• Build the project if needed

• Start the MCP server with HTTP transport on port 3000

• Launch MCP Inspector in your browser

• Provide endpoints:

  • Health check: http://localhost:3000/health

  • MCP endpoint: http://localhost:3000/mcp

  • SSE endpoint: http://localhost:3000/sse

2. Local Development (STDIO)

This mode directly connects the MCP Inspector to the server process using standard input/output.

3. Docker with Real AWS (STDIO)

This will:

• Build the Docker image if needed

• Start a container with your AWS credentials

• Connect MCP Inspector via Docker exec

4. Docker with Real AWS (HTTP)

This will:

• Start a containerized HTTP server on port 3000

• Connect MCP Inspector to the HTTP endpoint

• Useful for testing HTTP-based integrations

5. Docker Compose with MinIO (Testing)

This will:

• Start MinIO S3-compatible storage

• Create test buckets: test-bucket-1, test-bucket-2

• Upload sample files for testing

• Start the S3 MCP server connected to MinIO

• Launch MCP Inspector

• Provide MinIO Web UI at http://localhost:9001 (login: minioadmin/minioadmin)

Advanced Options

Force Rebuild

Debugging Tips

1. Check container logs:

   # For Docker CLI mode docker logs aws-s3-mcp-server # For Docker Compose mode docker compose logs s3-mcp

2. Test endpoints manually:

   # Health check curl http://localhost:3000/health # MinIO health (Docker Compose) curl http://localhost:9000/minio/health/live

3. Access MinIO Web UI (Docker Compose only):

   • URL: http://localhost:9001

   • Username: minioadmin

   • Password: minioadmin

Cleanup

Troubleshooting

• Port conflicts: If port 3000 is in use, stop other services or change the port

• AWS credentials: Ensure your .env file has valid AWS credentials for Docker modes

• Build errors: Use --force-rebuild to rebuild Docker images

• Connection issues: Check that containers are running with docker ps

Quick Reference

Connecting to Claude Desktop

To use this server with Claude Desktop, you'll need to use STDIO transport (not the default HTTP transport) for direct process communication:

1. Edit your Claude Desktop configuration file:

   • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

   • Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Add the S3 MCP server to the configuration:

Docker Option for Claude Desktop 🐳

You can also configure Claude Desktop to use a running Docker container for the MCP server:

⚠️ Important Prerequisites: For this Docker configuration to work, you MUST first build and run the Docker container BEFORE launching Claude Desktop:

# 1. First, build the Docker image (only needed once or after changes) docker build -t aws-s3-mcp . # 2. Then start the container (required each time before using with Claude) # Using Docker Compose (recommended) docker compose up -d s3-mcp # Or using Docker CLI docker run -d --name aws-s3-mcp-server --env-file .env aws-s3-mcp

Without a running container, Claude Desktop will show errors when trying to use S3 tools.

The Docker configuration above uses exec to send MCP requests directly to the running container. No port mapping is required since Claude communicates directly with the container instead of through a network port.

Note: Ensure the container name in the configuration (aws-s3-mcp-server) matches the name of your running container.

Important: Please note the following when using the configuration above

• Replace AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY with your actual credentials

• S3_BUCKETS should contain a comma-separated list of buckets you want to allow access to

• AWS_REGION should be set to the region where your buckets are located

💣 If error occurs on Claude Desktop

If you encounter errors with the above configuration in Claude Desktop, try using absolute paths as follows:

Available Tools

list-buckets

Lists available S3 buckets that the server has permission to access. This tool respects the S3_BUCKETS configuration that limits which buckets are shown.

Parameters: None

Example output:

list-objects

Lists objects in a specified S3 bucket.

Parameters:

• bucket (required): Name of the S3 bucket to list objects from

• prefix (optional): Prefix to filter objects (like a folder path)

• maxKeys (optional): Maximum number of objects to return

Example output:

get-object

Retrieves an object from a specified S3 bucket. Text files are returned as plain text, while binary files are returned with limited details.

Parameters:

• bucket (required): Name of the S3 bucket

• key (required): Key (path) of the object to retrieve

Example text output:

Example binary output:

Security Considerations

• The server will only access buckets specified in the S3_BUCKETS environment variable

• AWS credentials must have appropriate permissions to the buckets

• Use the principle of least privilege when configuring AWS permissions

• For production use, consider using IAM roles with specific S3 permissions

Usage with Claude

When interacting with Claude in the desktop app, you can ask it to perform S3 operations like:

• "List all my S3 buckets"

• "Summarize PDF files in my-documents-bucket"

• "Get the README.txt file from my-documents-bucket"

Claude will use the appropriate MCP tool to carry out the request and show you the results.

License

MIT