MCP Apps Extension (SEP-1865): Anthropic and OpenAI Co-Author Standard for Interactive UIs Served by MCP Servers
GitHub (Model Context Protocol)·medium signal
MCP Apps, jointly authored by Anthropic and OpenAI core maintainers, standardizes delivery of interactive React-based dashboards, forms, and data visualizations from MCP servers to host applications like Claude and ChatGPT. The spec uses sandboxed iframes with JSON-RPC over postMessage for bidirectional communication. This addresses the most-requested MCP community feature and marks the first joint specification between the two competing labs.