Half-baked:

Half-baked: diz-se de algo que ainda não foi bem pensado ou que não está bem planejado

 “The trouble with Mick is that some of his ideas are good, but a lot of them are half-baked and can't be used. “

 “Editing a student newspaper is difficult because I get a lot of half-baked poems and stories from the kids, and they get upset if I don't publish them.” (www.englishclub.com)