Agree with/to/on

You "agree on" a specific subject or issue after having a debate with somebody.
You "agree with" somebody whenever you both come to the same conclusion.
You "agree to" specific terms after having a discussion with somebody.



agree with <the idea/opinion/point> = have the same opinion; agree with smn ale's assessment/recommendation/etc

▪️ I agree with Tom that this approach doesn't look promising. 



▪️ I agree with your assessment of the risk level for this project.

▪️ I agree with your recommendation to change the design of the website.

agree to sth /do sth = give approval; accept a proposed item

▪️ I can agree to this.  


▪️ Would you agree to these terms?


▪️ Can we agree to re-assign two FTEs form project A to project B?

▪️ The client has agreed to our proposed timeline for the project.


▪️ We think going with this approach is our best bet, but it will be a bit more expensive. Would you agree to that?



▪️ The team has agreed to use a new project management tool for this project.

agree on <a  matter under discussion>  = change the idea to be the same 
I agree with you on this one.; come to a mutual decision/agreement

▪️ We need to agree on the scope of the project before we can move forward with planning.

▪️ We need to agree on the methodology for data collection before we can start analyzing the results.

▪️ The stakeholders have agreed on the key performance indicators that will be used to measure the success of the project.