Adaptive human-machine interfaces (HMIs) enhance driver safety and comfort by tailoring information presentation. While existing research identifies key adaptation parameters, their practical application remains challenging due to the complexity of rule-based decision making and the limitations of current authoring tools. To address these issues, this paper introduces AHSL, a domain-specific language for efficiently specifying message adaptation logic. By unifying established adaptation parameters within a hierarchical structure, AHSL simplifies rule creation and improves readability. Usability testing demonstrates AHSL’s effectiveness in supporting intuitive and efficient decision logic development.