Model Context Protocol Blog

I’m happy to share two updates to the maintainer team: Clare Liguori is joining the Core Maintainer group, and Den Delimarsky is joining me as a Lead Maintainer. When we introduced the MCP governance model last summer, the goal was to make sure the protocol could keep growing without any one person becoming a bottleneck. That has held up well through two specification releases, the move to the Agentic AI Foundation (AAIF), and a steady increase in SEP volume, and these changes give the project the leadership capacity it needs for what comes next. ...

MCP tool annotations were introduced nearly a year ago as a way for servers to describe the behavior of their tools — whether they’re read-only, destructive, idempotent, or reach outside their local environment. Since then, the community has filed five independent Specification Enhancement Proposals (SEPs) proposing new annotations, driven in part by a sharper collective understanding of where risk actually lives in agentic workflows. This post recaps where tool annotations are today, what they can and can’t realistically do, and offers a framework for evaluating new proposals. ...

You’ve built an MCP server that works quite well, but now you’re wondering: How do I add richer UI elements? Custom auth flows? What about domain-specific conventions, like those for finance or healthcare? This is where extensions come in. They let developers layer new capabilities on top of the baseline MCP implementation without touching the core protocol. This allows us to keep things stable while also opening up room to experiment, learn, and build with the community’s needs in mind. ...