Extension:TwitterCards

The TwitterCards extension adds meta tags to enable Twitter cards on MediaWiki.

About Twitter cards
Twitter describes this feature like this:

“Twitter cards make it possible for you to attach media experiences to Tweets that link to your content. Simply add a few lines of HTML to your webpages, and users who Tweet links to your content will have a "card" added to the Tweet that’s visible to all of their followers. It would be really nice for articles, images, videos - everything linked from Wikimedia on Twitter could have a nice little preview on Twitter. The documentation is at Twitter cards - basically it involves adding some meta tags around existing content server-side.”

Resources

 * Feature request on Bugzilla
 * TwitterCards GitHub repository - work in progress
 * DreykhMetadata GitHub repository - metadata library
 * Twitter tool to Preview a Twitter Card