It pulls the best version of the image, corrects the source automatically (if necessary), and shows translated tags (e.g., twitter hashtags) and the artist. It shouldn't ask for the source/image unless you're trying to use it on an unsupported site. You'll still have to fill in the remainder of the tags manually. It currently supports:
@Cutter, when you're on the Bookmarklet page, give it a read. Near the top where it says "Post to Danbooru", don't open that link. Please drag that link to your bookmarks bar without opening it. That should create a new bookmark to that page. Then when you're on a Lofter post (or wherever), just hit that bookmark and you're in business. You should see it have the source link and load a preview image etc, like Talulah said. It's a little easier than copy pasting the source into the upload page. Give a shout if that doesn't work.
