interesting question

(Many of us, esl learners, find agree tricky (with prepositions

I agree with ... to have the same opinion
I am expressing an opinion about something or other.
I think that's a good idea too.

I agree to ... consent to , comply to , concur to
I am indicating a commitment of some kind.
I am giving my approval to something that will not happen without my approval.

I agree on ... shake hands on , ***** agreement on , settle on
I am *****ing a decision or an agreement of some kind ..at the end of a meeting , for instance