To shed light on the relevance of the various features, we finally examine the feature importance derived from the F TM+CE random forest models, as shown in Figure . Overall, the relative metal radius (r rel ) and the number of d electrons (N d ) emerge as the most influential factors. In agreement with our previous observations (vide supra), predictions for Cr and Mn complexes primarily rely on features associated with the metal center, while predictions for Ni complexes are driven by geometric information. Nevertheless, even in those cases, the incorporation of both electronic and structural descriptors remains crucial to predict the ground state spins of TM complexes in both individual metal subsets or full dataset. For more comprehensive information regarding the performance of random forest models and a detailed list of complexes with incorrect predictions, see Table and Table in the SI.