The phrase "agreement of both" is correct and usable in written English.
It can be used when referring to a consensus or mutual understanding between two parties.
Example: "The agreement of both parties was necessary to move forward with the project."
Alternatives: "mutual agreement" or "consensus of both".
She called for a "balanced" agreement of both revenue increases and spending cuts.
But the SNP said the legal action had now been withdrawn "with the agreement of both parties".
"It's vital any changes to the constitutional future of this country has the agreement of both of Scotland's governments.
Six senators, three of them Democrats, have written to Obama urging him to slow passage of the legislation and win the agreement of both parties.
Though William J. Mayo became the administrator in the practice, no important decisions were made without the full agreement of both brothers.
While Liverpool are free to cancel the deal this month, it is understood they will only do so with the agreement of both Real Madrid and Sahin himself.
State officials said that because such a change would require the agreement of both a local district and the union in the district, it was within the law.
Judgments were passed only with the agreement of both incumbents, and the death or abdication of one resulted in the retirement of the other.
(By the agreement of both parties and all major media outlets, everything, including rainfall averages and fantasy-football player rankings, must now be assessed in terms of their implications for the 2016 election).
So far the committee, while usually achieving consensus reports, has not had any significant effect on the willingness of parliament to enact bills both along party lines and with the agreement of both major parties.
He said there was a "strong possibility" that Hamas would agree to an Egyptian-brokered reconciliation deal, which proposes holding the elections with the agreement of both sides next June.
