In this paper we perform a critical study on the applicability and reliability of the semi quantitative model based on the local hard-soft acid-base (HSAB) principle in calculating the interaction energy for the inter-molecular interactions. In particular, the effects of basis sets, electron correlation, and electron partitioning methods on the calculation of interaction energy using the descriptors will be studied. The cases that we have considered for the present study are the Lewis acid-base interactions, specifically, the interaction of acids BH3 and BF3 with bases NH3 and CO. The interaction energy ranges from ca. -32 to -2 kcal/mol. Since these complexes are well studied by both experimental and other conventional theoretical methods, these serve as the benchmark systems for the study of the above-mentioned effects.