Frog acts as an oracle, initially working for the antagonist Manny Rat. His role involves fortune-telling, though Manny Rat openly scorns his abilities as fake, underscoring their strained dynamic. Frog adapts his methods, reading feet for divination when the Mouse Child explains the toys lack palms due to their permanently clasped hands. He mentions learning this technique from a Babylonian praying mantis, implying a background in esoteric practices.

During a significant encounter, Frog asks the protagonists about their future desires. The Mouse Child wishes for the Elephant to become his mother and the Seal his sister, envisioning family life in the toy store, a request Frog views skeptically due to its scale. In contrast, the Mouse Father desires autonomy, specifically wishing for their winding key to be removed to gain self-winding capability.

Frog's prophecies carry substantial narrative weight. He later observes the partial fulfillment of these predictions, notably the formation of a family unit. His role shifts beyond passive observation when he confronts Manny Rat during the antagonist's vengeful return, directly challenging him with the words, "No, no you don't! Not this time, Manny Rat!" This marks Frog's transition from subservience to active defiance. His arc concludes with integration into the protagonists' community, where the Mouse Child addresses him affectionately as "uncle Frog," signifying his accepted place within their found family.