What probably matters to youSection of the release
Unclear The finding does not say what the ui field is used for or what the other allow-listed symbol-keyed field is.
What
MCP (Model Context Protocol, the standard Claude Code uses to connect external tools) tools can now supply a uiMeta value, extracted from an allow-listed subset of the tool's _meta field, including a ui key. When present, this uiMeta is attached to the tool's internal info and then passed back out as _meta when the tool definition is built.
Why
This lets an MCP tool pass a small piece of UI-related metadata through Claude Code unchanged, so the host application or interface can use it, without that data being altered or stripped along the way.
