fastmcp-ts
The official TypeScript framework for building Model Context Protocol servers, clients and apps, handling protocol plumbing so a project can focus on its own tools, resources and prompts.
fastmcp-ts is the TypeScript counterpart to the Python FastMCP framework, built on version 2 of the official MCP TypeScript SDK. It turns plain TypeScript functions into MCP tools, resources and prompts, inferring input schemas automatically from any Standard Schema-compatible validation library such as Zod, Valibot or ArkType.
It speaks both the 2025 legacy MCP protocol generation and a 2026 modern generation at once: a server serves both, and a client negotiates automatically by probing once at connect and falling back to legacy when needed, so upgrading from an older version keeps existing code working against either kind of server. Handlers get logging, progress reporting, LLM sampling, user elicitation and per-session state through an ambient context, middleware and auth hooks are supported, and child servers can be mounted onto a parent with optional name-prefix namespacing.
A client API supports scoped automatic cleanup and sampling adapters that forward a server's LLM sampling requests to a chosen provider such as Anthropic or OpenAI. It installs from npm and includes an inspect and call CLI for testing a server with no build step.