  We study contact four-point amplitudes in the spinor-helicity formalism in
anti-de Sitter space. We find that these amplitudes can be brought to an
especially simple form, which we call canonical. Next, we classify consistent
contact amplitudes by requiring correct transformation properties with respect
to the AdS isometry algebra. Finally, we establish a connection between the
canonical form of AdS amplitudes and scalar multi-trace conformal primaries in
flat space.
