MCP Server SDK
You can build and deploy MCP servers on Cloudflare, using the workers-mcp package ↗, which provides an SDK for authorization, transport, and tool definition and discovery.
This guide and the accompanying examples will help you get started.
Model Context Protocol (MCP) ↗ is an open standard that connects AI systems with external applications. Think of MCP like a USB-C port for AI applications. Just as USB-C provides a standardized way to connect your devices to various accessories, MCP provides a standardized way to connect AI agents to different services.
- MCP Hosts: AI assistants (like Claude ↗ or Cursor ↗), AI agents, or applications that need to access external capabilities.
- MCP Clients: Clients embedded within the MCP hosts that connect to MCP servers and invoke tools. Each MCP client instance has a single connection to an MCP server.
- MCP Servers: Applications that expose tools, prompts ↗, and resources ↗ that MCP clients can use.
The MCP standard supports two modes of operation:
- Remote MCP connections: MCP clients connect to MCP servers over the Internet, establishing a long-lived connection using HTTP and Server-Sent Events (SSE), and authorizing the MCP client access to resources on the user's account using OAuth.
- Local MCP connections: MCP clients connect to MCP servers on the same machine, using stdio ↗ as a local transport method.
Cloudflare's MCP Server SDK, is designed to support remote MCP connections. Remote MCP connections allow MCP clients that run in web browsers, mobile apps, and other environments outside of the end-user's machine to connect to your MCP server, such as Claude.ai ↗, and other AI agents.
- Define tools by just writing TypeScript methods, in the same way you write RPC methods in Workers and Durable Objects.
- Authorization is built-in. The MCP Server SDK handles the hard parts of the OAuth flow for you.
- Transport over HTTP with Server-Sent Events (SSE) is built-in, with automatic hibernation of idle connections to reduce costs
- You can create stateful MCP Servers with the Agents SDK
- Your MCP server can be called by the Agents SDK, which is an MCP client
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