A new tick box has appeared on the GL Account card in Microsoft Dynamics NAV 2015, called Omit Default Description in Jnl (Omit Default Desc. in Jnl):
With this option selected, the GL Account is entered on a journal line with a blank description:
If the description has not been completed when you try and post the journal you will get the following error:
Note: This can only be used on journal lines, the functionality does not work when entering GL Accounts on sales and purchase documents.