The package system automatically downloads and installs anything an application package depends on. If it needs libraries they'll be downloaded. Thus, no reason to write down anything. If it complains about missing libraries then it's because you're missing a repository in the app. manager's list of repositories.
And even if you install directly from file with 'dpkg' (which doesn't download anything), a missing library will still be recorded and tried resolved when there's an opportunity (which could be just apt-get upgrade, or apt-get install -f)
