Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
agent [ˈeɪdʒənt] n (representative, spy) аге́нт; (COMM) посре́дник; (CHEM) реакти́в; (fig) фа́ктор
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.