The oxidation state of \(\mathrm{P}\) in \(\mathrm{PCl}_5\) is \(+5\). Since \(\mathrm{P}\) has five electrons in its valence shell, therefore, it cannot donate electron and cannot increase its oxidation state beyond \(+5\), Thus, \(\mathrm{PCl}_5\) cannot act as a reducing agent. It can act as oxidizing agent by itself undergoing reduction.