Which tool is primarily used for measuring angles?

The tool primarily used for measuring angles is the protractor. A protractor is specifically designed to measure the degrees of angles, allowing carpenters and builders to achieve precise angles needed for cuts and joints in their work. It typically features a semicircular or circular scale with markings indicating angle degrees, making it easy to align and read angles accurately.

While other tools like the square can be used to check for right angles or assist in layout work, they do not provide a measurement of angles in degrees. A tape measure is mainly for measuring linear distances rather than angles, and a level is used to ensure that surfaces are horizontal or vertical, not for measuring angles. The protractor stands out because it directly addresses the need for angle measurement, making it the correct choice for this question.