Forewords

Forewords are really important! Before people, especially the leaders, giving their command or order to instruct people do work on something, it is important to establish a relax and anxiety-free working environment. This is to make sure that the subordinates can work in a conducive and productive ambiance.
To illustrate this, Mr A states all the expectations in a strict and serious manner before he allows his workers to start their work. It's good to state what you want your workers to accomplish by the end of the day. However, your workers would be working anxiously and fearfully. Sometimes, this anxiety will impede a good result.
On the other hand, Mr B shares what he expects with his friends in a more subtle way. This will instantly boost the subordinates to give him a helping hand to get things done. Always, things can be done better in this way.
So, it's your choice whether you want to be Mr A or Mr B.