Where Nephi's books emphasize personal narrative and vision, Jacob's book reads as collected preaching, closer to sermon transcription than autobiography. Jacob identifies himself as having been consecrated a priest and teacher by Nephi before Nephi's death, and he writes with the authority of that office rather than as a witness recounting his own journey. His condemnation of plural marriage practiced without divine sanction, delivered directly to the men of his community, is among the most pointed ethical material in the small plates and has been read by later Latter-day Saint commentators in connection with the church's own later and contested history with plural marriage.
Jacob's book is short relative to Nephi's two books, and its final chapters shift briefly into further historical notice before Jacob explains that he is passing the record to his son Enos, setting up the sequence of brief, personally authored books that follows through the remainder of the small plates.
Jacob also records a visit from a figure named Sherem, who challenges Jacob's teaching about a coming Christ and demands a sign, a confrontation that ends with Sherem's death shortly after receiving one; the episode is one of the small plates' few extended dialogues between named individuals rather than sermon or narration alone.