New article, tag: error message should consist more information

When user creates too long article, there is error message:
"tag is too long"
There is no information about maximum length of article.

Test scenario
Pre-condition

1. User is logged in
2. Write article form is opened

Steps to reproduse

1. Fill "Titlle" and "Content" fields
2. Write tag text with length more than 30 charasters
3. Press "Create article" button

AR: "Tag *** is too long"
ER: "Tag *** is too long. It should be no longer then 30 characters"
As *** I mean long tag