Back in the day, I used to use Samurize or RainMeter on my Windows machines to output the current system info on the desktop. That way, if something started acting funky, I would have an idea of where to start looking – if RAM was starting to get full, closing a couple of larger programs would usually fix the issue. If the CPU was peaking, then I could easily fire up the Task Manager and kill the culprit, proving that violence sometimes is the answer.
On Android, there are plenty of ways to monitor your processor, battery, RAM usage, etc. However, there is really no way to monitor said information while continuing to do other tasks, since Android only allows one window in the foreground at a time. That's where Cool Tool, a simple resource monitoring app, comes into play.
Cool Tool is different than other resource monitors on Android because it has an option to stay on top of other windows or the notification bar, allowing you to constantly monitor your hardware statistics.