I use cool reader & kindle touch for E-reading. I've converted quite a few PDF/PRC files to mobi-format with Calibre & mobiReader-Software. Before creating the MOBI-files I added metadata like author, title, rating, comment & cover-picture.
After creating a MOBI-File with calibre (calibre then also creates a new cover.jpg, metadata.opf & title.mbp file) I copied only the Mobi-File to a new folder and opened it with MobiReader. MobiReader showed all Metadata although not knowing about *.opf & *.mpb file. So I suppose all metadata is also stored directly in the Mobi-file. It also worked the other way.
Unfortunately, when copying the *mobi-files to my android-phone (Galaxys2) or kindle touch, all metadata are lost except the cover-pictures.
For example Cool Reader shows all cover pictures but if you go for details no author, title, rating or description is seen. Therefore I also can not sort by author or title. It's also no help to copy the *opf & *.mpb files as well to the phone/kindle
On the Calibre-support-pages they say "Ask amazon or the programmer of the readers"
Any idea, how the metadata could be retrieved???
Thanks for your help