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.
Names in the bundleuiMeta
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
The finding does not say what the `ui` field is used for or what the other allow-listed symbol-keyed field is.