Automation on top of the existing game client is currently permitted.
Adding files to the directory hierarchy of the game is currently permitted. Modifying any existing files is not permitted.
Modifying the game client in any way is not permitted, this includes memory modification, code injection, client file modification, etc, and is considered a 'custom client.'
Viewing game client memory is currently permitted.
I highly recommend not running other player's scripts or mods on your own machine. Unless you can fully understand the scope of the code that you are running, this is very unsafe.
If you can safely read and run others' code, then you can probably write it yourself, which is much safer.