FastMCP

A TypeScript framework for building MCP servers capable of handling client sessions.

[!NOTE]

For a Python implementation, see FastMCP.

Features

• Simple Tool, Resource, Prompt definition
• Authentication
• Passing headers through context
• Session ID and Request ID tracking
• Sessions
• Image content
• Audio content
• Embedded
• Logging
• Error handling
• HTTP Streaming (with SSE compatibility)
• HTTPS Support for secure connections
• Custom HTTP routes for REST APIs, webhooks, and admin interfaces
• Edge Runtime Support for Cloudflare Workers, Deno Deploy, and more
• Stateless mode for serverless deployments
• CORS (enabled by default)
• Progress notifications
• Streaming output
• Typed server events
• Prompt argument auto-completion
• Sampling
• Elicitation
• Configurable ping behavior
• Health-check endpoint
• Roots
• In-memory transport for unit testing without binding a port
• CLI for testing and debugging

When to use FastMCP over the official SDK?

FastMCP is built on top of the official SDK.

The official SDK provides foundational blocks for building MCPs, but leaves many implementation details to you:

• Initiating and configuring all the server components
• Handling of connections
• Handling of tools
• Handling of responses
• Handling of resources
• Adding prompts, resources, resource templates
• Embedding resources, image and audio content blocks

FastMCP eliminates this complexity by providing an opinionated framework that:

• Handles all the boilerplate automatically
• Provides simple, intuitive APIs for common tasks
• Includes built-in best practices and error handling
• Lets you focus on your MCP's core functionality

When to choose FastMCP: You want to build MCP servers quickly without dealing with low-level implementation details.

When to use the official SDK: You need maximum control or have specific architectural requirements. In this case, we encourage referencing FastMCP's implementation to avoid common pitfalls.

Installation

npm install fastmcp

Quickstart