expression, noun
useless messenger; fool's errand; doing only as told
Idiomatic expression describing a person sent on an errand but unable to act independently, or the errand itself as a pointless task.
彼に任せても子供の使いで、結局自分でやる羽目になった。
Even if I left it to him, it was like a fool's errand, and I ended up doing it myself.
Not being able to handle such a simple negotiation is just like a useless messenger.