A method includes receiving a drilling parameter, a tool characterization parameter, and a formation model. The method includes generating a forward model of a tool response at a bed boundary using the one drilling parameter, the tool characterization parameter, and the formation model. The method includes predicting at least two azimuthal gamma logs using the forward model. The method includes determining that a difference between the at least two azimuthal gamma logs generates a confidence level that is greater than a confidence threshold. In response to determining that the difference between the at least two azimuthal gamma logs generates the confidence level that is greater than the confidence threshold, the method includes generating a well plan. The method includes outputting a command for controlling a trajectory in directionally drilling a wellbore within a formation associated with the formation model using the well plan.