Short and sweet:

简短和甜 ×

言简意赅 √

例句：

I got a letter yesterday from my son at college. It was certainly short and sweet. All it said was "Dear Mom, please send me a hundred dollars right away. Love, your son, Mike.我昨天收到我儿子从大学寄来的一封信。这封信可真是简短，全部内容就是：亲爱的妈妈，请马上给我寄一百块美元。爱你们的儿子，麦克。