Google is testing adding a “Mobile-Friendly” tag onto the front of the description lines of Google AdWords ads.

Here is how Google is displaying AdWords ads with the “Mobile-Friendly” tag.

And some from the AdWords footer in the mobile search results.

Some advertisers weren’t concerned about whether their sites were mobile friendly or not, as their traffic was coming exclusively from AdWords and not from Google Search.   But AdWords has included mobile friendliness as part of their ads quality since 2011.  But with Google testing adding “Mobile-Friendly” tags to AdWords ads, advertisers will probably want to have a closer look at whether their sites are truly mobile friendly or not.

Here is a comparison between an ad with the test tag and without.

For AdWords advertisers, check your landing pages with Google’s mobile friendly tester here.  You can also learn more about how Google looks at mobile-friendliness in our Google Mobile Friendly Algo Guide.  Even though advertisers might not want their landing pages showing up in Google Search results, it is assumed that Google is using the same criteria to determine whether a site is mobile-friendly or not.

It is unclear if this test will go mainstream or not, but it seems to be pretty tiny as I wasn’t able to replicate it in all mobile browsers.

Added: I have been asked to show examples where it shows “mobile-friendly” along with various annotations such as sitelinks.  Here are two more screenshots.

Update: A Google spokesperson confirmed this is a small test they are currently running but there are currently no plans to add this to AdWords ads.