Agree to/ Agree with/ Agree on

Agree to something: Give consent to; accede to
Agree to a suggestion, to agree to an action proposed by someone else.
e.g:
Russia and Spain agree to Cooperate In Energy Sector
We agreed to her suggestion


Agree with someone/ something: get on, be good for, suit; to approve of it
Agree with a person, opinion or policy
e.g:
The copy agrees with the original.
I don’t agree with some of the issues they have raised in the rating rationale


Agree on something:To come to terms, as in the details of a transaction, reach agreement on, settle on
Agree on a matter for decision, to agree on an action that is jointly worked out; have similar feelings about a specific matter
e.g:
Democrat Obama and Republican McCain agree on a range of issues that have divided the parties under Bush
Major EU states agree on tighter regulation