In this article a concept and first prototype realisations will be presented for a fault tolerant assembly tool and the effects to the other subsystems of the ROCCO robotic system. The tool integrates active and passive compliment elements, gripping devices and sensor systems. The features of the other subsystems such as the necessary kinematic and vehicle accuracy, which should be as low as possible due to the high payload and reach, the necessary kinematic and vehicle sensor systems, which should be as easy as possible due to the environmental conditions, the features of the control, which are dependent on the integrated sensors, all is dependent on the range of positioning faults, which are tolerated by the assembly tool. Additionally the off-line programming system is dependent on the gripping features: tool changes, gripping points, approach strategies must be considered and developed depending on the tool design. The different requirements and flexibilities concerning the masonry systems, used pallets, wall configurations, fault tolerance in all DOFs and quality checks will be matched by the presented assembly tool, which was developed under the approach of minimising the needed usage of sensor systems and simultaneously maximising the flexibility of use.