I am sure Mcdermott had to agree with it.
But hypothetically speaking- If Beane wanted Cooper and Mcdermott didn't, do you honestly think Mcdermott could say "no" if Beane presented the idea to him, especially since there is a glaring need at WR? Like how could he even justify saying no to that?
Again, I am not saying Mcdermott didn't want him- But whether he wanted him or not, I don't think he could have looked like a sane man and said "no" to the trade