E.g.:
Away and awake: You sense <follower's name> is in awful condition.
Asleep: You dream that <follower's name> is in awful condition.
Could be restricted to "a follower" instead of a name, only grouped followers' names, calibrated to experience level, skills, spells, etc. These add-on's are utilities yet can become creative, for example a thief skill or mage spell "eavesdrop <dir>" which would potentially show some of the same out-of-room information as this mod. The key to mods is making sure to program ideas highly likely to make it into a release because they don't bind the code into an unwanted trajectory.