Bring rigor to your AI agents. Trusted by 8,500+ developers, Leo is a lightweight Python SDK designed to integrate prompt optimization directly into your CI/CD pipelines or internal tools. Stop shipping prompts that only work "most of the time." Leo provides a structured way to optimize drafts into role-based instructions and automatically evaluates them against real-world test cases using G-Eval and Hallucination Accuracy metrics. It's the missing piece of the LLM DevStack.