The bug
The error messages of the /tag <targets> add|remove
do not contain the affected tag nor the affected entity.
/tag @s add test
/tag @s add test
→ "Target either already has the tag or has too many tags"
/tag @s remove test
/tag @s remove test
→ "Target does not have this tag"
The success messages contain both the affected entity and the tag.
Is this still an issue in the latest snapshot 16w44a? If so please update the affected versions.
This is an automated comment on any open or reopened issue with out-of-date affected versions.