-(defun notmuch-search-archive-thread ()
- "Archive the currently selected thread (remove its \"inbox\" tag).
+(defun notmuch-search-archive-thread (&optional unarchive)
+ "Archive the currently selected thread.
+
+Archive each message in the currently selected thread by applying
+the tag changes in `notmuch-archive-tags' to each (remove the
+\"inbox\" tag by default). If a prefix argument is given, the
+messages will be \"unarchived\" (i.e. the tag changes in
+`notmuch-archive-tags' will be reversed).