clichè

"Keep me on my toes" is a clichè that means "keep me alert, aware, and prepared" so you will not get caught off-guard (off-guard is yet another clichè).

Hardly, barely, scarcely imply a narrow margin by which performance was, is, or will be achieved.

Hardly, though often interchangeable with scarcely and barely, usually emphasizes the idea of the difficulty involved: We could hardly endure the winter.

Barely emphasizes the narrowness of the margin of safety, “only just and no more”: We barely succeeded.

Scarcely implies a very narrow margin, below satisfactory performance: He can scarcely read.