That would be a bullfloat.
It is also important to control the 'dry time'
If concrete dries (cures) to fast, you will have more problems than just cracking (which ANY concrete is eventually going to do).
It will break off in chunks or sheets, if cured too rapidly.
On a hot day, there is a material that is sprayed onto the wet concrete, that will prevent the moisture from escaping too rapidly.
Try not to pour on days above 80* or below 40*.