What probably matters to youSection of the release
What
The SDK is the kit developers use to drive Claude Code from their own programs. It defines control requests, the commands a client can send to steer a session. That list now includes mcp_read_resource, which reads a resource from an MCP server, an external tool Claude Code connects to. It only accepts addresses beginning with ui://. Any other address is refused.
Why
Programs built on the SDK can fetch interface resources from MCP servers directly. The ui:// limit keeps other kinds of resource out of reach through this request.
