AWS S3 MCP Server

AWS S3 MCP Server

A Model Context Protocol (MCP) server that gives AI assistants (Claude, Cursor, etc.) direct access to AWS S3 — enabling them to list, upload, download, and manage S3 buckets and objects through natural language.

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Why This Exists

When building AI agent pipelines, you often need agents to read from or write to S3 — whether that's fetching documents for RAG, persisting outputs, or managing files dynamically. This MCP server bridges that gap by exposing S3 operations as MCP tools, so any MCP-compatible AI client can interact with S3 without custom integration work.

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Prerequisites

• Node.js 18+
• AWS account with S3 access
• AWS credentials (Access Key ID + Secret, or IAM role)
• An MCP-compatible client (Claude Desktop, Cursor, etc.)

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Quick Start

1. Install via npx (no installation needed)

{
  "mcpServers": {
    "aws-s3": {
      "command": "npx",
      "args": ["@gangadharrr/aws-s3"],
      "env": {
        "AWS_REGION": "us-east-1",
        "AWS_ACCESS_KEY_ID": "your-access-key-id",
        "AWS_SECRET_ACCESS_KEY": "your-secret-access-key"
      },
      "autoApprove": ["list_buckets", "list_objects", "get_bucket_policy"]
    }
  }
}

Add this to your MCP client config file:

• Claude Desktop: ~/Library/Application Support/Claude/claude_desktop_config.json
• Cursor: .cursor/mcp.json in your project root

2. Using AWS CLI credentials (recommended for local dev)

If you've already configured the AWS CLI (aws configure), you can omit the key env vars:

{
  "mcpServers": {
    "aws-s3": {
      "command": "npx",
      "args": ["@gangadharrr/aws-s3"],
      "env": {
        "AWS_REGION": "us-east-1"
      }
    }
  }
}

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Available Tools

Tool	Description
list_buckets	List all S3 buckets in the account
create_bucket	Create a new S3 bucket
delete_bucket	Delete an empty S3 bucket
list_objects	List objects in a bucket (with optional prefix filter)
upload_object	Upload a file or string content to a bucket
download_object	Download an object from a bucket
delete_object	Delete an object from a bucket
get_bucket_policy	Get the policy attached to a bucket
set_bucket_policy	Set or update a bucket policy

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Tool Reference

list_buckets

Lists all S3 buckets in the AWS account.

Parameters: None

Response:

{
  "success": true,
  "buckets": [
    { "name": "my-bucket", "creationDate": "2023-01-15T00:00:00.000Z" }
  ],
  "count": 1
}

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create_bucket

Creates a new S3 bucket.

Parameters:

Name	Type	Required	Description
bucketName	string	✅	Name of the bucket to create
region	string	❌	AWS region (defaults to configured region)

Response:

{
  "success": true,
  "bucketName": "my-new-bucket",
  "location": "http://my-new-bucket.s3.amazonaws.com/"
}

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list_objects

Lists objects in a bucket with optional prefix filtering.

Parameters:

Name	Type	Required	Description
bucketName	string	✅	Bucket to list objects from
prefix	string	❌	Filter by prefix (folder path)
maxKeys	number	❌	Max results (default: 1000)
continuationToken	string	❌	Pagination token

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upload_object

Uploads a file or string content to S3.

Parameters:

Name	Type	Required	Description
bucketName	string	✅	Target bucket
key	string	✅	Object key (path) in the bucket
filePath	string	❌	Local file path to upload
content	string	❌	String content to upload directly
contentType	string	❌	MIME type of the content

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download_object

Downloads an object from S3.

Parameters:

Name	Type	Required	Description
bucketName	string	✅	Source bucket
key	string	✅	Object key (path) to download
outputPath	string	❌	Local path to save the file
returnContent	boolean	❌	Return content inline in response

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delete_object

Deletes an object from a bucket.

Parameters:

Name	Type	Required	Description
bucketName	string	✅	Bucket containing the object
key	string	✅	Object key to delete

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get_bucket_policy / set_bucket_policy

Get or set the IAM policy for a bucket.

Parameters for set_bucket_policy:

Name	Type	Required	Description
bucketName	string	✅	Target bucket
policy	string/object	✅	Policy document (JSON string or object)

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AWS Authentication

The server uses the AWS SDK credential resolution chain in this order:

1. Environment variables — AWS_ACCESS_KEY_ID + AWS_SECRET_ACCESS_KEY
2. Shared credentials file — ~/.aws/credentials (configured via aws configure)
3. EC2 Instance Metadata — if running on an EC2 instance with an IAM role

For production, IAM roles are recommended over static credentials.

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Contributing

Contributions are welcome! If you'd like to add a new S3 operation or improve existing ones:

1. Fork the repository
2. Create a feature branch: git checkout -b feature/my-new-tool
3. Commit your changes: git commit -m 'Add: new S3 tool'
4. Push and open a Pull Request

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License

MIT — see LICENSE for details.

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Built with the MCP TypeScript SDK and AWS SDK v3.