The following Fargo.io script will insert a #glossary directive followed by a customStylesScripts macro that includes open graph meta tags for title, url, and description. I have tested this in Google's Structured Data Testing Tool and Facebook's Open Graph Object Debugger and it works. With these tags in place, you should be able to post a Fargo blog post to Facebook and have the open graph meta tags properly parsed.
To make this work, you need to add the script below to your menubar.opml file. Write your blog post, then put the cursor on the title of the post, and choose the add meta og script. Everything you need will be automatically written. By default, the description tag pulls the first line of your blog post. You can edit it afterwards if you want.