mcp-langchain-ts-client

What is mcp-langchain-ts-client?

It is a LangChain.js client for the Model Context Protocol (MCP), ported from the Python library rectalogic/langchain-mcp to the JavaScript/TypeScript ecosystem.

How to use mcp-langchain-ts-client?

Install via npm install mcp-langchain-ts-client. Create an MCPToolkit instance with server parameters (command and args), call await toolkit.initialize(), then access toolkit.tools to retrieve LangChain.js‑compatible tools. The tools can be passed directly to LangChain agents, for example using createReactAgent from @langchain/langgraph/prebuilt.

Key features of mcp-langchain-ts-client

• LangChain.js integration for Model Context Protocol tools.
• MCPToolkit class to spawn and manage MCP servers.
• Extracts MCP tools as LangChain.js StructuredTool instances.
• Supports any MCP server runnable via command line.
• Simple initialization and tool retrieval workflow.

Use cases of mcp-langchain-ts-client

• Connect a LangChain agent to MCP‑compatible tools (e.g., @modelcontextprotocol/server-everything).
• Build LangGraph workflows that leverage MCP server resources.
• Port Python‑based MCP‑LangChain integrations to JavaScript/TypeScript projects.

FAQ from mcp-langchain-ts-client

What is the relationship to rectalogic/langchain-mcp?

This package is a port of the Python library rectalogic/langchain-mcp to the JavaScript/TypeScript LangChain and MCP APIs.

What runtime does it require?

It requires Node.js (implied by npm installation and use of npx to launch MCP servers).

How do I obtain LangChain‑compatible tools from an MCP server?

Create an MCPToolkit instance with the server’s command and arguments, call initialize(), then access the tools property.

Does it work with any MCP server?

It works with any MCP server that can be launched as a subprocess using a command and args (e.g., @modelcontextprotocol/server-everything).