The Layer-Oriented Simulation Tool (LOST) is a code for simulating the performance of multiconjugate adaptive optics modules that uses a layer-oriented approach. It calculates atmospheric layers as phase screens, and then calculates the phase delays caused by these screens on the wave fronts of natural guide stars through geometrical optics approximations. This simulation considers the impact of wave-front sensors on measurement phase noise when combining wave fronts optically or numerically. The LOST code is explained in a dedicated publication. It was used for the estimation of the performance of the two layer-oriented modules MAD and NIRVANA, specifically the Multiconjugate Adaptive Optics Demonstrator for the Very Large Telescope and the Near-IR-Visible Adaptive Interferometer for Astronomy for the Large Binocular Telescope.