Why do cutting tools have sharp …

The cutting edges of tools like blades, knives etc., are provided with sharp edges to cut the things easily as the sharp edges has small area on which the force is applied, hence more pressure is applied.
Explanation:
As we know Pressure = Force/Area
From the above mathematical expression we can say that the pressure applied on a body is inversely proportional to the area on which the force is applied, the pressure exerted on a small surface area is more than the pressure exerted on the large surface area.
So we can conclude that equal force can exert higher pressure on a small area. This is why the cutting edges of tools like blades, knives etc., are provided with sharp edges to cut the things easily. The high pressure at the end of these sharp surfaces can easily pierce through wooden, plastic etc.,  surfaces.