LangChain overhauls MCP support: moves into main package on FastMCP v4
hwchase17 · x · 2026-09-05
LangChain announced revamped MCP protocol support as MCP usage grows fast. Key points:
- MCP support now lives in the main langchain package: uv pip install 'langchain[mcp]'.
- Built on FastMCP v4, which handles protocol negotiation, tool name conflicts, connection lifecycle, transports, auth, and caching.
- Supports MCP elicitation (human-in-the-loop) via interrupts.
- Adds listtools caching so agents don't re-fetch tools each run — a common TTFT pain point.
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