Unclear Whether the ReadWidgetContext tool is available by default, or only when something switches it on, is not shown.
What
An MCP server is an outside service that gives Claude extra tools. Some of them provide an MCP App, which shows you an interactive view. A new tool, ReadWidgetContext, lets Claude read the latest state such a view has sent to Claude Code, in other words what the view has shared.
- Each view is identified by the ID of the tool call that opened it. A tool call is one use of a tool by Claude. An app opened outside a tool call is identified by its thread instead.
- A reminder next to your message lists the IDs of the views whose shared state Claude Code is holding.
- The state Claude reads is marked as untrusted data, not as instructions to follow.
For programs built on Claude Code, user prompts now also carry widgetViews and widgetViewsMore fields.
Why
Claude can now take into account what you did inside an MCP App view. Because that state is treated as data rather than instructions, a view cannot use it to tell Claude what to do.
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Whether the ReadWidgetContext tool is available by default, or only when something switches it on, is not shown.