FastMCP 4.0 Release | Meet Nate Nowack, New Lead Maintainer

FastMCP just shipped its biggest release the same week Nate Nowack, Senior Software Engineer at Prefect, officially takes over as lead maintainer. In this episode, Jeremiah and Nate cover why the MCP protocol went fully stateless, what's new in FastMCP 4, and the latest maintainer war stories. What we cover: - Why Nate is stepping in as FastMCP's new lead maintainer - The open source maintainer's dilemma - MCP's new spec, released at end of July - FastMCP v4! Extensions, background tasks, and Docket - Why sampling got deprecated - LangChain adopting FastMCP as its default MCP client - How to upgrade to FastMCP 4 without breaking your server Timestamps: 0:00 – FastMCP's biggest release yet 0:42 – Nate takes over as FastMCP lead maintainer 1:30 – From Marvin to Control Flow: how FastMCP got started 5:00 – The origin story: "this went from fun to work real fast" 6:19 – The maintainer problem: 80%+ AI-generated PRs 9:15 – Fake security reports and GitHub injection attacks 13:24 – FastMCP v4: MCP protocol goes fully stateless 16:45 – Extensions explained: apps, tasks, and the meta field 19:10 – Background tasks and Docket, the scheduler behind them 21:34 – Why sampling got deprecated 23:34 – Claude's push for full MCP spec conformance 24:56 – Skills over MCP: ending the "MCP vs skills" debate 26:21 – Skills over MCP vs. plugins: what's the real difference 28:12 – The MCP servers Nate and Jeremiah actually use day to day 30:23 – Why elicitation had to change 34:55 – LangChain adopts FastMCP as its default MCP client 36:38 – Solving tool name collisions across multiple servers 41:37 – Upgrading to v4: what you need to know Resources: FastMCP docs: https://gofastmcp.com/getting-started/whats-new GitHub: https://github.com/PrefectHQ/fastmcp If this was useful, subscribe! We're always posting about production-ready workflows and AI agent infrastructure. X: @PrefectIO