MCP Server S3

What ofershap/mcp-server-s3 MCP server does

The ofershap/mcp-server-s3 MCP server connects an MCP client to AWS S3. It provides operations for discovering buckets, browsing keys, reading text content, writing text content, deleting objects, checking bucket availability, and creating presigned URLs for temporary access.

This is intended for tasks where an agent needs direct S3 operations without requiring the user to construct AWS CLI commands. Typical requests include listing available buckets, finding objects below a prefix, downloading a configuration file as text, uploading notes, or generating a link that expires after a specified period.

How it works

The ofershap/mcp-server-s3 MCP server runs locally through the npm package and communicates with the client over MCP. AWS authentication follows the default credential chain: environment variables are checked first, then the shared credentials file at ~/.aws/credentials, followed by IAM role credentials when the process runs in a supported AWS environment such as EC2, ECS, or Lambda.

The AWS identity used by the host must have permissions appropriate to the requested operations. The documented permissions include s3:ListBuckets, s3:ListBucket, s3:GetObject, s3:PutObject, s3:DeleteObject, and s3:HeadBucket. Region selection comes from AWS_REGION, which defaults to us-east-1 when not set.

Setup and configuration

Install and start the server with npx mcp-server-s3. MCP client configuration passes the command and AWS settings in the server environment. The README provides configurations for Cursor, Claude Desktop, and VS Code. Cursor users can also load the repository as a local Agent Plugin from ~/.cursor/plugins/local/mcp-server-s3.

Set AWS_REGION and provide AWS_ACCESS_KEY_ID plus AWS_SECRET_ACCESS_KEY when using environment-based credentials. Alternatively, make the shared AWS credentials file or an instance/container IAM role available to the process. The project does not provide OAuth or AWS SSO wiring through its Agent Plugins package.

Tools and capabilities

The available tools are:

• list_buckets: returns all buckets visible in the AWS account.
• list_objects: lists objects in a selected bucket, with optional prefix filtering and a count limit.
• get_object: retrieves an S3 object and reads its contents as text.
• put_object: writes supplied text content to an object key.
• delete_object: removes an object from a bucket.
• presigned_url: creates a temporary URL for an object.
• bucket_info: checks whether a bucket exists and returns basic information.

Limitations and notes

The ofershap/mcp-server-s3 MCP server documents text upload and text reading rather than general binary file handling. Access is governed by the AWS permissions of the configured identity, so a tool call can fail if the identity lacks the corresponding S3 action. Credentials are expected to remain in the client host environment or its AWS credential sources; the README specifically notes that one-click installation is not offered because secrets cannot be embedded in a portable install link. The project is MIT licensed and includes development commands for type checking, building, testing, formatting, and linting.