For the sake of debugging a problem, sometimes it's useful to have an app that has an "at a glance" output of various different Facebook features / endpoints. This is just such a tool.
It doesn't attempt to skin itself as a full app. It's just a dashboard of information and one click access to various Facebook Dialogs and other publishing endpoints, like OG Actions and /feed. It also displays the latest status of the API, pulled directly from Facebook.
Facebook provides a tool which allows you to make arbitrary calls against the Graph API. But to help you eliminate any possible errors in your infrastructure, Diagnostics comes with a fully functional version of that tool, so that you can makes those calls from your own systems, without having to write a line of code.
Page Tab & Canvas developers are provided with a wealth of information via a
POST when the user initially lands on your app. The initial view of Diagnostics provides a clean and simple display of what Facebook is telling you, with full explanations of each field, to help you plan your landing experience with real data.
Invoke the many available dialogs from the handy dropdown menu. Responses are printed back to the screen to test your JS.