Mineral dust affects the West African energy balance and monsoon circulation, yet climate models differ widely in the dust optical properties that set the balance between scattering and absorption. As a result, models disagree even on whether dust produces net shortwave (SW) warming or cooling over North Africa. Here we show that Saharan single-scattering albedo (SSA), an observable intensive optical property, accounts for much of the inter-model spread in the shortwave dust forcing response across climate models. The Saharan SW effective radiative forcing due to aerosol&ndash;radiation interactions (<strong>ERF_ari^SW</strong>) decreases systematically with increasing SSA, shifting from near-zero or positive values in lower-SSA, more absorbing models to negative values in higher-SSA, more scattering models. Applying an Aerosol Robotic Network (AERONET)-based observational constraint on SSA, 0.9543 &plusmn; 0.0060, gives a constrained Saharan <strong>ERF_ari^SW</strong> centered near zero at &minus;0.66 W m^&minus;2, with a 95 % interval of &minus;3.87 to +2.53 W m^&minus;2.</p> <p>Grouping the models by SSA reveals two contrasting monsoon responses to the same dust-emission perturbation. Low-SSA models show stronger atmospheric heating over the Sahara, a deeper heat low, enhanced monsoon inflow, and increased Sahel rainfall, whereas High-SSA models show a weaker or opposite response and reduced rainfall. The associated cloud-radiative response forms a Sahel&ndash;tropical North Atlantic dipole. Propagating the SSA-based constraint on the <strong>ERF_ari^SW</strong> through the relationship between Saharan <strong>ERF_ari^SW</strong> and Sahel cloud-radiative response reduces its inter-model variance by about one third. Thus, an observable dust optical property constrains a significant part of the downstream monsoon and cloud-response uncertainty.