Christine Yoder argues in an article on Proverbs 30 that Agur’s exhortation to humility and his puzzling observations are deliberately placed at the climax of the book so that the experience of reading the book actually inculcates the wisdom that the book talks about.
She sums up the message of chapters 28-29 this way:
“At the close of Prov 28-29, readers are poised for the invitation to ‘come up here’ (Prov 25:7) and assume a position of leadership. Schooled further by court scribes and adept with more proverbs of Solomon, they are nuanced in their thinking about the possibilities and perils of authority and government, and alert to a moral arena defined largely in terms of ‘[the] people[s]’ (28:12,15,28; 29:2,18; cf. also ‘a land’ in 28:2; 29:4), rich and poor (e.g., 28:3,6, 8,11), wicked and righteous, wise and foolish. Presumably, they are also optimistic about the accessibility of wisdom and their capacity to interpret the world and navigate its complexities intelligently. In terms of pedagogical and thematic development, therefore, we expect readers to be asked next to identify with King Lemuel, whose mother elaborates on royal justice, particularly with regard to the poor (Prov 31:1-9). But Proverbs turns instead to Agur.”Agur is much less confident of his access to wisdom. He is weary and self-professedly ignorant. He thinks of himself as a brute, and blurs the distinction between human and animal behavior. He even questions the whole of kingship, the goal toward which Proverbs moves: “Particularly noteworthy for those on the threshold of kingship is Agur’s comparison of a king to creatures that are stately in their stride (the lion, rooster, and he-goat, 30:29-31)—which Agur follows immediately with a warning against self-exaltation (30:32-33)—and Agur’s description of the royal office as vulnerable to unprepared leaders (30:22) and stealthy infiltrators (i.e., the lizard, 30:28). A king may not even be necessary, Agur observes, for the locusts march tightly in rank without one (30:17; cf. Joel 2:7-8a).
Thus, “Readers who successfully navigate through Prov 30 arrive at the threshold of kingship with a heightened awareness of the complexities inherent to being wise.”