This is a very simple plugin, that does it's job quickly and does it's job well. No configs, permissions, or commands are needed. It needs Vault and "prefix" metadata to work. This is given by most major permissions systems.
How does it work?
For each player, it finds the first two characters of their "prefix" metadata. This is usually a colour code, for example &c. This is used to format the prefix in chat, so why not the TAB list?
Since the TAB list can only support up to 16 characters, and the colour code takes up 2, usernames over 14 characters are automatically shortened and given a ".." on the end, so you know their full name isn't displayed.
Disclaimer: This plugin was not made by me, but for me. I paid for this, and am letting the public make use of it. Therefore, treat it 'as is' without ANY support given should it not work.