One embodiment of the present invention provides a system that determines the locations and dimensions of one or more assist features in an uncorrected or corrected mask layout. During operation, the system receives a mask layout. The system then creates a set of candidate assist feature configurations, which specify locations and sizes for one or more assist features in the mask layout. Next, the system determines an improved assist feature configuration using the set of candidate assist feature configurations and a process-sensitivity model which can be represented by a multidimensional function that captures process-sensitivity information. Note that placing assist features in the mask layout based on the improved assist feature configuration improves the manufacturability of the mask layout. Moreover, using the process-sensitivity model to determine the improved assist feature configuration reduces the computational time required to determine the improved assist feature configuration in the mask layout.