What probably matters to youSection of the release
What
A new SDK control request, mcp_read_resource, lets a host application read a single ui://-scheme resource from a connected MCP server using the resources/read method. It's read-only and doesn't trigger a model turn. It comes with a full schema, defined error handling, and a size limit, and is advertised during session setup as the mcp_read_resource_v1 capability.
Why
This gives host applications a way to fetch MCP Apps UI resources (part of the SEP-1865 proposal for richer MCP UI integrations) directly and cheaply, without needing to route the request through a model turn.
