diff --git a/7d2d236668872cf11f167ac0462f8751/description b/7d2d236668872cf11f167ac0462f8751/description
index 488a279..1bfe147 100644
--- a/7d2d236668872cf11f167ac0462f8751/description
+++ b/7d2d236668872cf11f167ac0462f8751/description
@@ -1,13 +1,19 @@
-add `ent tag ISSUE_ID TAG`
+add `ent tag ISSUE_ID [-]TAG`
 
-Tags are short text strings without white space.
+If the optional "-" is not supplied, the TAG is *added* to the ISSUE.
+
+If the "-" *is* supplied before the TAG, the TAG is *removed* from
+the ISSUE.
+
+Tags are short text strings without white space, and not beginning with
+"-".
 
 The Issue directory will gain a file named `tags`, containing the sorted
 list of tags.
 
 The `ent list` output will add a bit to the end of each issue displayed,
 something like "[tag1, tag2]", or nothing if the issue has no tags
-(like how we don't show assignee if there is none).
+(like how we don't show assignee if it is None).
 
 As part of this issue, the `ent list FILTER` will gain a new filter
 chunk type like "tags=v2.31,ux-papercut".