Cool band names are very subjective.
Also, bands and their names often become cool only after they become popular.
For instance, many think that the Rolling Stones is a cool band and band name.
But if you take a similar naming convention and named your band the Tumbling Pebbles, that may not sound very cool to you.
In short, I think you could name your band almost anything you want and, if your music is popular, your band and band name will likely achieve cool status.
That said, many popular bands use simple words in their names like the Rolling Stones, Coldplay, the Beatles, the Beach Boys, etc.
With this in mind, throw a fun word in the generator and see what comes up!