He wrote a scholarly volume on ecclesiastical terms, which was well received in his time; however, today he is perhaps best known for his short book on the Vitues of Coffee published in 1671.
He returned to Rome in 1623 accompanied by twelve Maronite students, who came to study at the College of the Propaganda Fide, recently founded by Pope Urban VIII.
He was in the service of Cardinal Francesco Maria Brancaccio, Bishop of Viterbo, where he was appointed Canon Theologian of his Cathedral Chapter.
In 1644 Magri published in Italian the first edition of an encyclopaedia of ecclesiastical terms - Notitia De Vocaboli Ecclesiastici, reissued in Latin in 1677.
Finally, he published the eighteen page pamphlet Virtu del Kafe, Bevanda Introdotta Nuovamente Nell’Italia con alcune osservationi per conservar la sanità nella vecchiaia.