Succinct means said in very few words, and said well. Short, and nothing missing.
The praise is essential, since something succinct is not merely brief but complete despite being brief, which is what separates it from curt or abrupt. A succinct summary, a succinct answer, a succinct explanation. It is a compliment writers and editors hand out sparingly. The adverb succinctly usually attaches to put, and the noun succinctness is rare enough that most people say brevity instead.
Succinct is belted up. Latin succīnctus meant girdled, with the clothes gathered in tight so they would not trail, and being brief is that same tucking-in done to words.
Proto-Indo-European
*upó — from below; up
Latin
succīnctus — belted, girdled; enclosed or tightly wrapped; (figurative) concise, succinct; etc.
Old French
succinct
Middle English
succinte
English, today
succinct
Built from
The is derived from Late Middle English succinte, succynt (“having one’s waist encircled with something, girdled; brief, concise, succinct”), borrowed from Old French succinct (modern French succinct), or directly from its Latin succīnctus (“belted, girdled; enclosed or tightly wrapped; (figurative) concise, succinct; etc.”), the of succingō (“to gather or tuck up with a belt, etc.”), from suc- (a variant of sub-, ultimately from Proto-Indo-European upó (“from below; up”)) + cingō (“to encircle, surround; to gird”) (further etymology uncertain). The is derived from the adjective.
Etymology from Wiktionary, CC BY-SA