LangChain AI Updates: September 4, 2026

1. MCP Moves Into the Core LangChain Package and Goes Stateless

LangChain. MCP support graduates from the separate langchain-mcp-adapters package into the main library under langchain.mcp, installed with pip install "langchain[mcp]". The implementation now sits on FastMCP for transports, auth, connection management, and protocol negotiation, so it speaks both the old and new MCP specifications. The updated spec drops the stateful session-based architecture for a stateless core, removing the need for sticky routing and shared session stores. Two new features land alongside it: elicitation, which pauses tool execution to request user input and surfaces as a LangGraph interrupt for human-in-the-loop approval, and client-side tool list caching enabled with cache=True. Python is supported now, with TypeScript planned. Source