npm package: @iflow-mcp/samuraikun-aws-s3-mcp
Description: MCP Server for S3
Author: Yuichi Kojima
Latest version: 0.4.0

# S3 MCP Server

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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

## 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:

```bash
# Install globally via npm
npm install -g aws-s3-mcp

# Or as a dependency in your project
npm install aws-s3-mcp
```

2. If building from source:

```bash
# Clone the repository
git clone https://github.com/samuraikun/aws-s3-mcp.git
cd aws-s3-mcp

# Install dependencies and build
npm install
npm run build
```

3. Configure AWS credentials and S3 access:

Create a `.env` file with your AWS configuration:

```
AWS_REGION=us-east-1
S3_BUCKETS=bucket1,bucket2,bucket3
S3_MAX_BUCKETS=5
AWS_ACCESS_KEY_ID=your-access-key
AWS_SECRET_ACCESS_KEY=your-secret-key
```

Or set these as environment variables.

## Configuration

The server can be configured using the following environment variables:

| Variable                | Description                                       | Default           |
| ----------------------- | ------------------------------------------------- | ----------------- |
| `AWS_REGION`            | AWS region where your S3 buckets are located      | `us-east-1`       |
| `S3_BUCKETS`            | Comma-separated list of allowed S3 bucket names   | (empty)           |
| `S3_MAX_BUCKETS`        | Maximum number of buckets to return in listing    | `5`               |
| `AWS_ACCESS_KEY_ID`     | AWS access key (if not using default credentials) | (from AWS config) |
| `AWS_SECRET_ACCESS_KEY` | AWS secret key (if not using default credentials) | (from AWS config) |

## Running the Server

### Direct Node.js Execution

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

```bash
# Using npx (HTTP transport by default)
npx aws-s3-mcp

# If installed globally (HTTP transport)
npm install -g aws-s3-mcp
aws-s3-mcp

# If running from cloned repository (HTTP transport)
npm start

# Or directly (HTTP transport)
node dist/index.js

# Explicit HTTP transport
node dist/index.js --http

# STDIO transport (for Claude Desktop integration)
node dist/index.js --stdio
```

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:

```bash
docker build -t aws-s3-mcp .
```

2. Run the container with environment variables:

```bash
# Option 1: Pass environment variables directly
docker run -d \
  -e AWS_REGION=us-east-1 \
  -e S3_BUCKETS=bucket1,bucket2 \
  -e S3_MAX_BUCKETS=5 \
  -e AWS_ACCESS_KEY_ID=your-access-key \
  -e AWS_SECRET_ACCESS_KEY=your-secret-key \
  --name aws-s3-mcp-server \
  aws-s3-mcp

# Option 2: Use environment variables from .env file
docker run -d \
  --env-file .env \
  --name aws-s3-mcp-server \
  aws-s3-mcp
```

3. Check container logs:

```bash
docker logs aws-s3-mcp-server
```

4. Stop and remove the container:

```bash
docker stop aws-s3-mcp-server
docker rm aws-s3-mcp-server
```

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:

```bash
# Build and start the container
docker compose up -d s3-mcp

# View logs
docker compose logs -f s3-mcp
```

2. To stop the container:

```bash
docker compose down
```

#### Using Docker with MinIO for Testing

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

```bash
# Start MinIO and the MCP server
docker compose up -d

# Access MinIO console at http://localhost:9001
# Default credentials: minioadmin/minioadmin
```

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

```bash
# Show all available options
./run-inspector.sh --help

# Run locally with HTTP transport (default)
./run-inspector.sh

# Run with Docker Compose and MinIO for testing
./run-inspector.sh --docker-compose
```

### 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)

```bash
# Default: HTTP transport for local debugging
./run-inspector.sh

# Explicit HTTP transport
./run-inspector.sh --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)

```bash
# STDIO transport for local debugging
./run-inspector.sh --stdio
```

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

#### 3. Docker with Real AWS (STDIO)

```bash
# Create .env file with your AWS credentials
cp .env.example .env
# Edit .env with your AWS credentials

# Run with Docker using STDIO transport (default for Docker)
./run-inspector.sh --docker
```

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)

```bash
# Run with Docker using HTTP transport
./run-inspector.sh --docker --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)

```bash
# Run with MinIO for local testing (no AWS credentials needed)
./run-inspector.sh --docker-compose
```

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

```bash
# Force Docker image rebuild
./run-inspector.sh --docker --force-rebuild
./run-inspector.sh --docker-compose --force-rebuild
```

#### Debugging Tips

1. **Check container logs**:

   ```bash
   # For Docker CLI mode
   docker logs aws-s3-mcp-server

   # For Docker Compose mode
   docker compose logs s3-mcp
   ```

2. **Test endpoints manually**:

   ```bash
   # 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

```bash
# Stop and remove Docker containers
docker stop aws-s3-mcp-server && docker rm aws-s3-mcp-server

# Stop Docker Compose services
docker compose down

# Stop specific HTTP server container
docker stop aws-s3-mcp-http-server && docker rm aws-s3-mcp-http-server
```

### 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

| Command                               | Transport | Environment    | Description                              |
| ------------------------------------- | --------- | -------------- | ---------------------------------------- |
| `./run-inspector.sh`                  | HTTP      | Local          | Local development with HTTP transport    |
| `./run-inspector.sh --stdio`          | STDIO     | Local          | Local development with STDIO transport   |
| `./run-inspector.sh --docker`         | STDIO     | Docker + AWS   | Docker container with AWS credentials    |
| `./run-inspector.sh --docker --http`  | HTTP      | Docker + AWS   | Docker container with HTTP transport     |
| `./run-inspector.sh --docker-compose` | STDIO     | Docker + MinIO | Local testing with MinIO (no AWS needed) |

## 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:

```json
{
  "mcpServers": {
    "s3": {
      "command": "npx",
      "args": ["aws-s3-mcp", "--stdio"],
      "env": {
        "AWS_REGION": "us-east-1",
        "S3_BUCKETS": "bucket1,bucket2,bucket3",
        "S3_MAX_BUCKETS": "5",
        "AWS_ACCESS_KEY_ID": "your-access-key",
        "AWS_SECRET_ACCESS_KEY": "your-secret-key"
      }
    }
  }
}
```

### Docker Option for Claude Desktop 🐳

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

```json
{
  "mcpServers": {
    "s3": {
      "command": "docker",
      "args": ["exec", "-i", "aws-s3-mcp-server", "node", "dist/index.js"],
      "env": {}
    }
  }
}
```

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

```bash
# Get the path of node and aws-s3-mcp
which node
which aws-s3-mcp
```

```json
{
  "globalShortcut": "",
  "mcpServers": {
    "s3": {
      "command": "your-absolute-path-to-node",
      "args": ["your-absolute-path-to-aws-s3-mcp/dist/index.js", "--stdio"],
      "env": {
        "AWS_REGION": "your-aws-region",
        "S3_BUCKETS": "your-s3-buckets",
        "S3_MAX_BUCKETS": "your-max-buckets",
        "AWS_ACCESS_KEY_ID": "your-access-key",
        "AWS_SECRET_ACCESS_KEY": "your-secret-key"
      }
    }
  }
}
```

## 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:**

```json
[
  {
    "Name": "my-images-bucket",
    "CreationDate": "2022-03-15T10:30:00.000Z"
  },
  {
    "Name": "my-documents-bucket",
    "CreationDate": "2023-05-20T14:45:00.000Z"
  }
]
```

### 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:**

```json
[
  {
    "Key": "sample.pdf",
    "LastModified": "2023-10-10T08:12:15.000Z",
    "Size": 2048576,
    "StorageClass": "STANDARD"
  },
  {
    "Key": "sample.md",
    "LastModified": "2023-10-12T15:30:45.000Z",
    "Size": 1536000,
    "StorageClass": "STANDARD"
  }
]
```

### 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:**

```
This is the content of a text file stored in S3.
It could be JSON, TXT, CSV or other text-based formats.
```

**Example binary output:**

```
Binary content (image/jpeg): base64 data is /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof...
```

## 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