A recent breakthrough by Kogan and Parter (SODA ’22) gave the first polynomial improvement in decades for the size‑diameter trade‑off of shortcut sets. However, most algorithmic applications have not exploited these bounds because many occur in decentralized settings, and we lack decentralized algorithms that achieve the Kogan‑Parter guarantees. We therefore study the communication complexity of constructing Kogan‑Parter shortcut sets. The edges of an $n$‑node directed graph are split between two players, Alice and Bob, who also receive a target diameter $D$. Our main result is a protocol that, for $D \le n^{1/3}$, lets Alice and Bob agree on a shortcut set matching the Kogan‑Parter size‑diameter trade‑off while exchanging only $\tilde O\left(\frac{n^2}{D^2}\right)$ bits. We also provide (non‑matching) lower bounds on the communication needed to find any $D$‑diameter shortcut set of arbitrary size. The key technical ingredient for the upper bound is a low‑communication path‑cover protocol, a common subroutine in shortcut‑set constructions that has attracted independent interest. Our protocol deliberately avoids the use of Menger’s theorem or antichain decompositions, which are typical in prior work. For the lower bounds, we relate the communication complexity of the shortcut‑set problem to the size of bridge‑free path systems, yielding hardness results.\n\nReview: This work bridges the gap between recent theoretical advances and practical decentralized algorithms by providing a concrete communication upper bound and a novel path‑cover technique, offering valuable directions for future research.