Getting LLMs to reliably call tools in production is not just a prompting problem but also a training problem but most practitioners lack a principled way to measure progress. This talk uses tau2-bench, a rigorous tool-calling benchmark, as the backbone for a complete fine-tuning workflow: generating training scenarios, running supervised fine-tuning, and applying reinforcement learning to push past the ceiling of imitation. The result is a model measurably better at domain-specific tool use with concrete before/after numbers. Practitioners leave with a reusable approach: use a structured benchmark to drive your fine-tuning loop, not just to evaluate at the end.