Thirteen per-app control tools are registered but every call returns "not available in this build" without a host implementation.
A new tier of computer-use tools operates a single application through Accessibility instead of taking over the whole display: app_screenshot, app_click, app_type, app_key, app_scroll, app_drag, app_menu, app_list_windows, app_ax_find, app_batch, app_release, app_bring_to_current_space and list_apps. They only work when the host program running Claude Code provides an app-scoped implementation; otherwise every call returns "Per-app background tools are not available in this build."
- Each call re-checks an enabled flag, so remote configuration can switch the family off part-way through a session. When that happens the message is "Per-app background control (the app_* tools) was just turned off for this device by a remote configuration change."
- app_screenshot returns a JPEG plus an <ax-summary> listing interactive elements; the indices in that summary can be passed back as element_index to click or type into a specific control.
- None of these tool names existed in v2.1.241, and the implementation module moved position in the bundle.
Per-app background tools are not available in this build.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.