In the rapidly evolving landscape of Industry 4.0, the Asset Administration Shell (AAS) is a fundamental building block for developing digital twins. This paper presents an innovative approach to automatically generate Application Programming Interfaces (API) for AAS-based systems from a formalized specification. So far, the convention was to manually specify the API for AAS by tedious translation of the abstract specification published in form of a book. We propose, instead, to formalize the abstract specification, and automatically translate it into API. We thus streamline the development process, ensure effectiveness, and minimize the risk of errors in the representation of digital twins otherwise inherent in the manual procedure. Our proposed approach places great importance on automating the development of AAS APIs, using common and widespread YAML/OpenAPI as a serialization format due to its clarity and simplicity. Additionally, the paper examines other Interface Descriptions such as Protobuf, SOAP, GraphQL, and WSDL, emphasising the significance of clearly defined interfaces for efficient AAS API utilisation. Our method guarantees scalability and flexibility, specifically in relation to SDK generation, whereby different AAS interfaces are generated to support smooth integration within the constantly changing landscape of Industry 4.0. This comprehensive approach facilitates the entire lifecycle of digital twin development, spanning from API generation to SDK development, to ensure resilient and adaptable solutions agnostic to particular serialization formats.