This intermediate-level talk demonstrates how to leverage Language Model Query Language (LMQL) for structured generation and tool usage with open-source models like Llama. You will learn how to build a RAG system that enforces output constraints, handles tool calls, and maintains response structure - all while using open-source components. The presentation includes hands-on examples where audience members can experiment with LMQL prompts, showcasing real-world applications of constrained generation in production environments.