-(defcustom notmuch-message-replied-tags '("replied")
- "Tags to be automatically added to or removed from a message when it is replied to.
-Any tag in the list will be added to a replied message or,
-if it is prefaced with a \"-\", removed.
+(defcustom notmuch-message-replied-tags '("+replied")
+ "List of tag changes to apply to a message when it has been replied to.
+
+Tags starting with \"+\" (or not starting with either \"+\" or
+\"-\") in the list will be added, and tags starting with \"-\"
+will be removed from the message being replied to.