Born in Brescia, Agosti graduated in direction at the Centro Sperimentale di Cinematografia and specialized in editing at the Gerasimov Institute of Cinematography in Moscow.

[1][2] After directing several shorts and serving as film editor in Marco Bellocchio's Fists in the Pocket, he made his feature film debut in 1967 with Garden of Delights, which was heavily cut from censorship.

[1][2] In the following years he mostly focused on socio-political documentaries, dealing with themes such as the protests of 1968, of the resistance against the 'Colonels' regime in Greece, and the strategy of tension.

[2] In the second half of the 1970s, Agosti founded in Rome the cineclub Azzurro Scipioni, which became a reference point for art cinema filmmakers and film buffs.

[3] In 1992, he won the Ciak d'Oro for best editing for his film Uova di garofano.