MCP to LangChain Tools Conversion Library / TypeScript

A simple, lightweight library to use Model Context Protocol (MCP) server tools from LangChain.

Project Status

This library currently supports MCP Protocol version 2025-03-26. It does not support the MCP 2026-07-28 specification.

For new projects, we recommend using LangChain’s official LangChain.js MCP Adapters library, which provides comprehensive MCP integration for LangChain.

This project is now in maintenance / dormant mode. Existing users may continue using it with MCP servers compatible with the 2025-03-26 specification, but new MCP protocol features will not be actively implemented here.

Introduction

A simple, lightweight library to use Model Context Protocol (MCP) server tools from LangChain.

Its simplicity and extra features, such as tools schema adjustments for LLM compatibility and tools invocation logging, make it a useful basis for your experiments and customizations. However, it only supports text results of tool calls and does not support MCP features other than Tools.

LangChain’s official LangChain.js MCP Adapters library, which supports comprehensive integration with LangChain, has been released. For new projects, it is the recommended MCP integration path for LangChain.

Prerequisites

• Node.js 18+
• [optional] npm 7+ (npx) to run Node.js package-based local MCP servers
• [optional] uv (uvx) installed to run Python-based local (stdio) MCP servers

Installation

npm i @h1deya/langchain-mcp-tools

Quick Start

convertMcpToLangchainTools() utility function accepts MCP server configurations that follow the same structure as Claude for Desktop, but only the contents of the mcpServers property, and is expressed as a JS Object, e.g.: