This app only has one purpose - it uses the unofficial android market api to get info about other apps that are on the Google Play Store. It can get info about an app's description, category, price, etc. on the Google Play Store. The info is used in other apps (like ROM Toolbox or Ultimate Backup) to create app groups or show you additional information about one of your installed apps.
The reason this is a separate app is because of the permissions it requires. This app is open source, which means you can know exactly what the app does. The permissions to your accounts is only used to generate a token used in the Android Market API. This is explained here: http://code.google.com/p/android-market-api/wiki/WithAndroid
We didn't want to just add those permissions to the main app. This same API is used by apps like Titanium Backup. We just made this a separate app so users won't complain so much about a permission being added :P
If you have any additional questions please feel free to contact us at firstname.lastname@example.org