Comment # 13 on bug 990425 from Andreas Stieger

If you restrict the search to the Documentation:Tools project, it is shown
correctly:

> $ zypper ar --refresh --check obs://Documentation:Tools doc
> $ zypper search -r doc -t application calibre
> Loading repository data...
> Reading installed packages...
> 
> S | Name                 | Summary                                        | Type       
> --+----------------------+------------------------------------------------+------------
>   | Calibre Ebook Reader | The one stop solution to all your e-book needs | application

Also:

> zypper search -r doc calibre
> Loading repository data...
> Reading installed packages...
> 
> S | Name                 | Summary                                        | Type       
> --+----------------------+------------------------------------------------+------------
>   | Calibre Ebook Reader | The one stop solution to all your e-book needs | application
>   | calibre              | EBook Management Application                   | srcpackage 
>   | calibre              | EBook Management Application                   | package    
>   | calibre-debuginfo    | Debug information for package calibre          | package    
>   | calibre-debugsource  | Debug sources for package calibre              | package    
>   | calibre-test         | Calibre Test Package                           | package    
>   | calibre-test         | Calibre Test Package                           | srcpackage 

As such SR#415147 / r354 seems to fix the issue.