A conlang optimized for poetic expression would exhibit at least the following features:
1. A low tolerance for consonant clusters in codas. This creates fewer possible rhymes, which decreases the possibilities for syllables to not rhyme with each other. Rhyme and assonance are perhaps the most important auditory qualities of poetry, given that vowels are more acoustically salient than other phonemes.
2. A medium-sized vowel inventory (i.e., one containing 5-6 vowels). A smaller vowel inventory increases the likelihood of rhyme, but a larger vowel inventory can be deployed to create a less monotonous, richer, and more varied aesthetic/phonosymbolic effect.
3. A fixed stress system and an iambic rhythm type (meaning that primary stress is invariably on the ultimate syllable and secondary stress is always on the antepenultimate syllable). This is perhaps ideal for fixed verse forms in that stressed line-final syllables are salient phonological and temporal markers that create a particularly strong resonance between words.
4. A high degree of inflexion and phonological fusion, since this minimizes the amount of consecutive unstressed syllables.