Today’s blockchain technologies focus mostly on isolated, proprietary technologies, yet there are application scenarios that ask for interoperability, e.g., among blockchains themselves or with external applications. This paper proposes the Smart Contract Locator (SCL) for the unambiguous identification of smart contracts over the Internet and across blockchains, and the Smart Contract Description Language (SCDL) for the abstract description of the external interface of smart contracts. The paper derives a unified metamodel for blockchain smart contract description and equips it with a concrete, JSON-based description language for smart contract search and discovery. The goal of the proposal is to foster smart contract reuse both inside blockchains and through the integration of smart contracts inside enterprise applications. The idea is inspired by the Service-Oriented Architecture (SOA) and aims to provide a high-level, cross-blockchain interoperability layer.