Visiting the desktop version of a website while on mobile is typically not desirable. A big, clumsy site can take quite a while to load properly, sometimes leaving you wondering why you went there in the first place. Google is attempting to combat that, introducing some alerts to let us all know when we’re about to chart desktop territory.
The first tool is for the webmaster, where Google Webmaster Tools will let you know when a site on your domain isn’t mobile friendly. Whether it’s a page, or the entire site, Google wants it compliant, and has begun sending messages to those in change of websites to alert them if they’re out of order.
The second change affects users, where a message will show up if you’re about to migrate to a desktop site. Noted as a utility in Search — but likely to appear elsewhere, too — Google will tell you the site you’re about to visit has a habit of sending you to a desktop site. You can, of course, still visit the site, but at least you know ahead of that slow status bar dragging across the top of your screen that you might be in for the long haul.
This is another way Google is attempting to lure everyone into a mobile-friendly world. If a webmaster starts to see traffic decline as a result, they’re probably just going to make changes to win mobile visitors back. At least, it seems that’s what Google is hoping for.