Eleutherodactylus jasperi is a relatively small frog with adults reaching 22.4 mm in snout-vent length. Males and females are the same size. This frog has a bluntly rounded snout which is almost truncate when viewed from above, and an indistinct canthus rostralis. The tympanum is indistinct. Prevomerine teeth are lacking. The digits have only vestigial webbing and are moderately long with rounded terminal discs. Subarticular tubercles are prominent but metatarsal tubercles are absent. Palmar tubercles are small but distinct. The dorsum is shagreened (with small bumps), with well-developed subdermal glands on the flanks and the posterior surfaces of the thighs. The venter is areolate in texture. Dorsally, the color is a uniform olive-gold to yellow-gold. If the frog is disturbed, the color may pale. Ventrally, the coloration is pale yellow except for transparent abdominal skin. Few to no melanophores appear to be present on the ventral surfaces of the head and abdomen. The iris is pale gray with black speckles (Drewry and Jones, 1976).

Eleutherodactylus jasperi can be distinguished from other Eleutherodactylus in Puerto Rico by its golden ground color without dorsal patterning, by its translucent venter without dark pigmentation, and by the lack of prevomerine teeth (Drewry and Jones, 1976).