Using zone calculations in the FLAPW (the full-potential linearized augmented-plane-waves) model, the information on the energy, charge and spin characteristics of Pt$_{1-x}$Au$_x$MnSb ($x$ = 0–1) alloys is obtained. As established, the interatomic spatial electron density decreases, covalent bonds weaken, and the cohesive energies of the alloys decrease with an increase in the concentration of Au atoms in Pt$_{1-x}$Au$_x$MnSb alloys. As found, the dominant contribution to the formation of magnetic moments in Pt$_{1-x}$Au$_x$MnSb alloys is made by the 3$d$ electrons of manganese atoms. In alloys with $x$ = 0.25 and $x$ = 0.5, the total polarization of Fermi electrons is registered, which converts these alloys to the half-metallic state.