To add some salt to this thread: Why not even adding the upstream URL into the debian/control file?
I´m in the process of building a list of all biology relevant packages in Debian to let him have a look what exists in the free software world. A simple grep-available biology would serve all necessary information. Currently I have to install all those programs, went to /usr/share/doc/<program> and browse the copyright file. This is boring. I can see reasons that an additional controll field URL might perhaps change to much. But I would consider it as "good habit" if the description would include the upstream URL. At least I will think about doing so in my packages in future uploads. Kind regards Andreas. CC to debian-policy@lists.debian.org