What should you look for when visually inspecting power tools before use?

When visually inspecting power tools before use, looking for external defects is crucial as it directly relates to safety and the tool's operation. External defects can include cracks, frayed cords, loose parts, or any signs of damage that could affect the tool's performance or pose a risk to the user. Identifying these issues beforehand can prevent accidents or malfunctions when the tool is in use.

While the other aspects mentioned are important, they do not address the immediate condition of the tool in a way that can prevent potential hazards. Dust accumulation, for instance, could indicate a lack of maintenance but does not directly reflect the tool's safety. Checking the battery level is significant for battery-operated tools, but it is more about usability than safety. Warranty validity is related to the financial aspects of tool ownership and does not pertain to the tool's immediate safety and operational integrity.