If you're editing the metadata with Calibre, Calibre can add the metadata to the beginning of the book when you convert that book. Just go to Preferences/Common Options/Structure Definitions and put a checkmark in the box that says "Insert metadata as page at start of book. You should be aware that when this option is checked, Calibre will put the metadata at the start of the book
every time you convert that book. You can easily end up with the description repeated several times at the beginning of the book. Ask me how I know this.
As for which readers will see the metadata, I'm not aware of any that make the description available when you're looking at a list of your books. When sideloading with Calibre, Sony and Kindle readers both use series and tag information to put books into Collections. For readers that support folders, Calibre will create folders using metadata as part of saving to disk.