The very first thing that the test automation tool has is the support for multi-platform so that even the future needs of the users could easily be fulfilled. The overall usability of the script should be high and the tool must have some basic or advanced jailbreak requirements.
This is because there are users who often install a customized ROM on their devices and the violation of MDM policies often creates issues. Next is the ability of the tool to support the new versions of the OS. If possible, the tool should be capable of sharing the source code.