Let $\mathcal{T}$ be a triangulated category, and let $\mathcal{A}:=\operatorname{End}(\mathcal{T})$ be the category of triangulated endofunctors of $\mathcal{T}$.
Is $\mathcal{A}$ triangulated?
My suspicion is no, due to the lack of functoriality of mapping cones, but yes if $\mathcal{T}$ possesses an enhancement in the sense of Bondal-Kapranov.
Thanks!