Google recently announced that you can now use Webmaster Tools to track your site’s usability in mobile browsers. I checked a couple of my sites and the information given was wrong for both, so it seems to be pretty useless at the moment.
However, what they don’t mention is that their PageSpeed Insights has been updated to cover mobile (and desktop) usability. And testing some pages from the same sites I looked at in Webmaster Tools, the PageSpeed tool actually gives accurate information!
It’s well worth running a page from your site through the tool to see how it fares. Of course, you don’t have to follow all the suggestions it makes, but it may well point out an issue that you didn’t notice before. In my case it pointed out that many of my JPEG images could be losslessly optimised.