The essay examines a manuscript written by Giovanni Camillo Sagrestani dated March 1, 1715. The title page of this collection is Ritratti di diversi pittori and the manuscript is held at Biblioteca Nazionale Centrale di Firenze (BNF Palatino 473). This compilation is a sort of dossier with twenty-five pen and ink portraits of Venetian painters copied from Le Maraviglie dell'arte by Carlo Ridolfi, in some cases enriched with brief information about the subjects' lives. On the final page of the document, the Florentine painter added a previously unknown biography of Antonio Magliabechi. After Sagrestani's death, the manuscript became the property of Francesco Maria Niccole Gabburri, and it was overlooked until now. This article focuses on the historiographic skills of Sagrestani, who also wrote two well-known collections of Vite di artisti. In his Ritratti, the author refers to famous painters such as Paolo Veronese and Jacopo Tintoretto, but also to overlooked artists like Sante Peranda and Pietro Malombra. By seeking to clarify the reasons behind the creation of this document, which was written during the span of time between the publications of the posthumous last two volumes of Filippo Baldinucci's Notizie de'professori in 1704 and 1728, this research examines the Florentine context in which Sagrestani provided his information. This paper particularly analyses the Medici family's appreciation for the artists mentioned in this manuscript, and the knowledge of them by contemporary scholars. The second part of this study demonstrates the deep connection established by Sagrestani with Magliabechi, since the biography devoted to the famous librarian of the Medici family is one of the earliest tributes to him after his death on July 4, 1715. Indeed, the manuscript reported habits and characteristics of Magliabechi's lifestyle, defending him against the attacks made to his good reputation.