MCP TypeScript SDK

[!IMPORTANT] This is the main branch which contains v2 of the SDK (currently in development, pre-alpha).

We anticipate a stable v2 release in Q1 2026. Until then, v1.x remains the recommended version for production use. v1.x will continue to receive bug fixes and security updates for at least 6 months after v2 ships to give people time to upgrade.

For v1 documentation and code, see the v1.x branch.

Overview

The Model Context Protocol (MCP) allows applications to provide context for LLMs in a standardized way, separating the concerns of providing context from the actual LLM interaction.

This repository contains the TypeScript SDK implementation of the MCP specification and ships:

• MCP server libraries (tools/resources/prompts, Streamable HTTP, stdio, auth helpers)
• MCP client libraries (transports, high-level helpers, OAuth helpers)
• Runnable examples (under examples/)

Packages

This monorepo publishes split packages:

• @modelcontextprotocol/server: build MCP servers
• @modelcontextprotocol/client: build MCP clients

Both packages have a required peer dependency on zod for schema validation. The SDK internally imports from zod/v4, but remains compatible with projects using Zod v3.25+.

Installation

Server

npm install @modelcontextprotocol/server zod

Client

npm install @modelcontextprotocol/client zod

Quick Start (runnable examples)

The runnable examples live under examples/ and are kept in sync with the docs.

1. Install dependencies (from repo root):

pnpm install

2. Run a Streamable HTTP example server:

pnpm --filter @modelcontextprotocol/examples-server exec tsx src/simpleStreamableHttp.ts

Alternatively, from within the example package:

cd examples/server
pnpm tsx src/simpleStreamableHttp.ts

3. Run the interactive client in another terminal:

pnpm --filter @modelcontextprotocol/examples-client exec tsx src/simpleStreamableHttp.ts

Alternatively, from within the example package:

cd examples/client
pnpm tsx src/simpleStreamableHttp.ts

Next steps:

• Server examples index: examples/server/README.md
• Client examples index: examples/client/README.md
• Guided walkthroughs: docs/server.md and docs/client.md

Documentation

• Local SDK docs:
  • docs/server.md – building MCP servers, transports, tools/resources/prompts, CORS, DNS rebinding, and deployment patterns.
  • docs/client.md – using the high-level client, transports, backwards compatibility, and OAuth helpers.
  • docs/capabilities.md – sampling, elicitation (form and URL), and experimental task-based execution.
  • docs/faq.md – environment and troubleshooting FAQs (including Node.js Web Crypto support).
• External references:
  • Model Context Protocol documentation
  • MCP Specification
  • Example Servers

v1 (legacy) documentation and fixes

If you are using the v1 generation of the SDK, the v1 documentation (and any v1-specific fixes) live on the long-lived v1.x branch. See: https://github.com/modelcontextprotocol/typescript-sdk/tree/v1.x.

Contributing

Issues and pull requests are welcome on GitHub at https://github.com/modelcontextprotocol/typescript-sdk.

License

This project is licensed under the MIT License—see the LICENSE file for details.