Server Connect: File Rename

I want to add a feature where users can rename files which have been uploaded to a website
(eg PDFs and images). The File Rename feature in Server Connect looked like the obvious choice, but I think perhaps it isn’t. There is File Path field for the original file name, with static or variable options. However it seems the new name has to be based on a template.

It would make this feature more useful if in addition to the template option, the new name could be assigned using a variable - or is this already an option?