Graded linear exponential comonads are an extension of linear exponential comonads with grading, and provide a categorical semantics of resource-sensitive exponential modality in linear logic. In this paper, we propose a concise double-category theoretic formulation of graded linear exponential comonads as a kind of monoid homomorphisms from the multiplicative monoids of semirings to the composition monoids of symmetric monoidal endofunctors. We also exploit this formulation to derive the category of graded comonoid-coalgebras, which decompose graded linear exponential comonads into symmetric monoidal adjunctions plus twists.