The latest version of Telligent Community adds open graph tags to the page by default, but doesn't add the tags required for Twitter to make use of those tags and show a preview of the content within the tweet, for example a tweet containing a link to a standard Telligent 9 install might look like this:
By enabling twitter card support you get something that looks more like this:
Adding basic twitter card support requires two extra meta tags to be added to the page: twitter:site and twitter:card.
You can use this plugin, to add these to every page on your community, in conjunction with the standard open graph tags added this should allow content about your content to be displayed in tweets.
The plugin goes a little further and will also try and add an image, and the content authors twitter handle if possible.
With certain types of content (Blog Posts and Media) you can define an open graph image, if that's set it will be used, otherwise the plugin will check to see if there is a featured image, or image attachment, and use that. If it finds one of these images it will also switch the Twitter Card type to be a Summary with Large Image.
If the user has set there Twitter profile field, there twitter username will be added to the header as the author of the specific content (the sites twitter username will still be passed as the site).
You can download the plugin and find instructions for installing it on GitHub.
If you have any questions, suggestions, or issues - get in touch, or raise an issue on GitHub. If you have any improvements please open a Pull Request on GitHub!
If you are looking for more control over the open graph tags and twitter cards check out the Meta Data Plugin from 4-Roads (this plugin also works with earlier versions of Telligent Community).