Off should mean the model is never told the tool exists. A switch that
only made the call fail leaves Hermes offering walkthroughs it cannot
give and promising to point at things it cannot point at, which reads as
a broken agent rather than a respected preference.
Both gate on the switch through a shared desktop_ui.user_enabled helper,
which is the reactions check_fn generalized — same config read, same
reason it has to be config rather than an env var: the switch belongs to
the session's client, and the client may be on another machine.
One generic tool in the desktop_ui toolset: discover what is on screen,
highlight an element with narration, or hand the user a paged tour. No tour
content lives in the code — the agent authors each one live, which is what
makes 'how does this work?' answerable as a walkthrough instead of a wall
of text.
Rides the existing blocking-prompt bridge (tour.request/.respond) like
read_preview, so it works on every connection topology.