@zambucco - there is no possible way to return this informaiton consistently. As calibre has some funky "merging" logic internally for the results of a metadata download across all the plugins you have enabled. So you can never (uness you only have one plugin enabled and/or have the field disabled for all the other plugins) guarantee that a tag or a description from one particular website is going to make it through to the end result that you see displayed on the download metadata dialog for setting against your book.
It is a calibre design limitation for metadata download plugins, one day someone will invest the time to come up with an enhanced API but until then the only real way around it is to write a standalone plugin to specifically download that sort of information and put it into a custom column. For instance someone one paid me to write a plugin that downloads the exact review score (with decimal places) and # reviews from Amazon and Goodreads to put into a custom column.
And yes I also find that award winners often do not live up to the hype either - but its always a bonus to find a cracking good book when one does