  We show that the Kontsevich-Segal (KS) criterion, applied to the complex
saddles that specify the semiclassical no-boundary wave function, acts as a
selection mechanism on inflationary scalar field potentials. Completing the
observable phase of slow-roll inflation with a no-boundary origin, the KS
criterion effectively bounds the tensor-to-scalar ratio of cosmic microwave
background fluctuations to be less than 0.08, in line with current
observations. We trace the failure of complex saddles to meet the KS criterion
to the development of a tachyon in their spectrum of perturbations.
