Agniolo was one of Leonardo da Vinci's assistants in Florence, and the first one mentioned. He was able to read and transcribe "Leonardo’s impenetrable scrawl". Alongside with Innocento, Agniolo oversaw Leonardo’s other assistants in 1480.
When Leonardo left for Venice, Agniolo remained behind to take care of his workshop together with Innocento and continued in this role throughout Leonardo’s absences. Agniolo was under strict orders to destroy notes concerning the designs from Altaïr Ibn-La'Ahad's Codex in case they were in danger of falling into the wrong hands.