Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
agreement [əˈgriːmənt] n (consent) согла́сие; (arrangement) соглаше́ние, догово́р
in agreement with в согла́сии с +instr
we are in complete agreement ме́жду на́ми по́лное согла́сие
by mutual agreement по взаи́мному соглаше́нию
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.