Ponytail is a decision-making framework for AI coding agents that prevents over-engineering. It prioritizes a structured approach: skip what doesn’t need to exist, reuse existing code, use stdlib/platform features, check installed dependencies, then write minimally. Real-world testing shows this achieves approximately 54% less code, 20% cheaper execution, and 27% faster generation while maintaining safety standards. For developers using AI code assistants who want production-ready, pragmatic suggestions.