Hermes is named as the giver of Pandora’s final gift in Hesiod’s Theogony.
Hesiod’s Theogony gives a compact account of Pandora’s creation and lists the roles of several gods. In that passage, Hermes gives Pandora a mind and a deceitful character, helping explain the deceptive nature of Zeus’s gift. The detail differs from the longer narrative emphasis in Works and Days.
Hermes is a fitting figure for this role because Greek mythology associates him with communication, exchange, boundaries, travel, and clever deception. He is also the messenger of the gods, although his functions are broader than simply carrying messages.
The answer is easy to confuse with Zeus, who orders Pandora’s creation and sends her to Epimetheus. Zeus is the planner of the episode, while Hermes is specifically credited in Theogony with giving Pandora her mental and deceptive qualities. This distinction comes from comparing Hesiod’s two accounts rather than relying on modern summaries.