Answer:
Maximum Shear Stress tells you if the failure of the material is going to happen.
Step-by-step explanation:
In the Maximum Shear Stress theory, the condition of failure in a component is when the Maximum Shear Stress is greater than the value of shear stress that corresponds to the yield point of the material (In books this value is also referred has the Yield strength in shear under tensile test). To prevent the failure (the safe design), the Maximum Shear Stress must be less or equal to permissible shear stress (note: the permissible shear stress is the value of shear stress that corresponds to the yield point of the material divide by a factor of safety).