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

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)

Setup

1. Install via npm:

# 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:

# 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

You can run the server with Node.js:

# Using npx (without installing)
npx aws-s3-mcp

# If installed globally
npm install -g aws-s3-mcp
aws-s3-mcp

# If running from cloned repository
npm start

# Or directly
node dist/index.js

Debugging on MCP Inspector

To debug the server using MCP Inspector, you can run sh run-inspector.sh

sh run-inspector.sh

Connecting to Claude Desktop

To use this server with Claude Desktop:

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:

{
  "mcpServers": {
    "s3": {
      "command": "npx",
      "args": ["aws-s3-mcp"],
      "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"
      }
    }
  }
}

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:

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

{
  "globalShortcut": "",
  "mcpServers": {
    "s3": {
      "command": "your-absolute-path-to-node",
      "args": ["your-absolute-path-to-aws-s3-mcp/dist/index.js"],
      "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:

[
  {
    "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:

[
  {
    "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