Sensory Characteristics prohibits instructions like Click the green button or See the square icon on the right when that description is the only way to identify the control. Instructions need a text-based identifier as well, such as a visible label or name, so the reference still works for someone who cannot perceive color, shape, or position the way a sighted mouse user does.
A common failure is instructing users to use the round button next to the price to add an item to cart, when the button has no accessible text label at all.