Described herein are systems, apparatus, and methods for precise placement and guidance of tools during a surgical procedure, particularly a spinal surgical procedure. The system features a portable robot arm with end effector for precise positioning of a surgical tool. The system requires only minimal training by surgeons/operators, is intuitive to use, and has a small footprint with significantly reduced obstruction of the operating table. The system works with existing, standard surgical tools, does not required increased surgical time or preparatory time, and safely provides the enhanced precision achievable by robotic-assisted systems.