Hello SharePointer :),
These days I am working with SharePoint 2013 master page and I see that, site description is not available, however we can display that using inbuilt SharePoint webcontrol control 🙂
just place below lines on your html master page where your div is looking for site description :
<!--MS:<SharePoint:ProjectProperty Property="Description" runat="server">--> <!--ME:</SharePoint:ProjectProperty>-->
And you will see all pages with site description.
Happy SharePointing !