LangChain integrates Model Context Protocol into main package with stateless core and elicitation support

LangChain has revamped its support for Model Context Protocol (MCP) by moving it into the main package (langchain.mcp) built on FastMCP, replacing the separate langchain-mcp-adapters install. This update supports elicitation via interrupts and client-side caching. The new stateless MCP spec eliminates session pinning, improving server reliability and scalability, and allows tool lists to be cacheable, preventing re-fetching on every run. MCP tool calls from ChatGPT users have increased 98x across 2026, more than doubling in August alone.