I recommend keeping all the files within a script bundle. All the files placed within a script or applet bundle serve an important purpose.
Script Debugger.plist file is sacrificial in that it contains state information that you may not want to retain - window position, view settings, breakpoints, expressions, code signing settings, copyright notices, version numbers, etc. Loosing this information will not impact the script’s execution, but you should be certain you want this information discarded.
description.rtfd files should be retained. This is your script’s description, and once these files are removed, that information cannot be recovered. If you are certain you never will have a description for your script(s), I supposed these can go, but a blanket exclusion of these files may hurt you at some point in the future.
main.recover.rtf files are a judgement call. I recommend keeping them as they are source code backups of the AppleScript byte code stored in
main.scpt. They are required in those instances where the byte code becomes corrupted (rare, but it happens). This file also serves as the backing store for Script Debugger’s QuickLook generator and allows QuickLook (and by extension Script Debugger’s Open Quickly feature) to function without having to launch all the apps the script references.