Secondly, the amount of agreement and enforcement is placed squarely on the shoulders of the participant nations. The UN can't force anybody to act... it's just a forum for nations to come together and make agreements. No agreement in the UN is truly binding, it is also based on faith between the world of States.
But if States want to save face with their allies and partners, then they need to stick to their agreements. The world is still an anarchy at heart (according to POLISCI 101) and so agreements are abandoned or adhered to as it suits the needs and agendas of individual nations. This is the central reason why the UN's policy implementation is usually chaotic. There is no super power to bring out a stick and hit those who disobey.