I get 'Edits must be at least 6 characters; is there something else to improve in this post?' for fixing a typo on top of adding tags. Just adding tags would be fine.
Related to “Edits must be at least 6 characters”, why?, but different.
Editing tags doesn't count towards the "at least 6 characters" rule (unfortunately). So the answer is actually the same as on the linked question "Edits must be at least 6 characters", why?
I'm afraid this rule will continue to affect you for another 6-8 weeks or so, until you have gained enough reputation (now 2000) to "Edit Questions and Answers".