I am trying to upload txt file(4,073 bytes) through iTunes Connect to manage content of one of my apps. It didn’t allow me to upload and said file size is more than 4000 Characters. Then, I removed couple of characters from the file manually and uploaded the txt file (4,045 bytes) and it was accepted by iTunes Connect.
Not sure how do I restrict/determine the size of the txt file? Since I have an automated tool which basically generates the file with 4000 bytes/characters limit, which obviously ignored by iTunes connect.
Your best option would be to set the limit to be 4,000 characters and just stick with that.
You never know when Apple will tighten up on the iTunesConnect application description field’s (possibly temporary) flexibility.