Like several other early bishops of Seleucia-Ctesiphon, he is included in the traditional list of patriarchs of the Church of the East.
Brief accounts of Tomarsa's episcopate are given in the Ecclesiastical Chronicle of the Jacobite writer Bar Hebraeus (floruit 1280) and in the ecclesiastical histories of the Nestorian writers Mari (twelfth-century), ʿAmr (fourteenth-century) and Sliba (fourteenth-century).
In all these accounts he is anachronistically called 'catholicus', a term that was only applied to the primates of the Church of the East in the fifth century.
He therefore reversed his wicked policy, made peace with Jovian, Julian’s chief commander, and ordered the churches to be restored.
He was a man of conspicuous virtue and sanctity, and devoted all his efforts to the restoration of the churches.