LangChain 1.4.0 adds a first-class MCP namespace and MCPAdapter

3 September 2026 (72-hour extension)

The official GitHub release lists a new langchain.mcp namespace and MCPAdapter, runnable MCP examples, model-destination inclusion in agent tool routing, and reduced middleware trace inputs.

Why it matters: MCP integration moving into the main package reduces adapter sprawl and makes tool routing easier to standardise across agent applications.

Business/technical/strategic impact: Teams should test backwards compatibility, elicitation handling, routing metadata, trace redaction and failure behaviour before upgrading production agents.

Confirmed by primary source; production reliability is not independently established. High