-tag). The '\\[notmuch-search-tag-all]' key can be used to add or remove a tag from all
-threads in the current buffer.
+tag). The '\\[notmuch-search-tag-all]' key can be used to add and/or remove tags from all
+messages (as opposed to threads) that match the current query. Use with caution, as this
+will also tag matching messages that arrived *after* constructing the buffer.