This contribution introduces a multiscale fracture model that aims to take the microstructural length scale effects into account in brittle failure. This model is formulated in the framework of Cosserat continuum theory and coupled with the phase field approach to failure to describe complex crack paths. The effectiveness of the proposed method is demonstrated using two cases: a shear crack propagation problem and a crack interaction problem. The first benchmark problem is proposed to reveal the synergistic aspect between Cosserat kinematic parameters and related energy distribution. This problem shows the importance of microstructural parameters on the resulting macroscopic crack path. An application case is then proposed to highlight the related consequences in terms of crack coalescence kinetics.