Evaluation

Evaluation-Driven Development of LLM Agents

Unlike deterministic systems, an LLM agent’s output is often probabilistic, meaning multiple responses may be valid within a given scenario.

Building product evals is simply the scientific method in disguise. That’s the secret sauce. It’s a cycle of inquiry, experimentation, and analysis.

The primary evaluation metric used in τ-bench is pass^k, which measures the probability that all k independent task trials are successful for a given task, averaged across all tasks. Unlike the pass@k metric that is common for other LLM evaluations (which measures if at least one of k trials succeeds), pass^k evaluates consistency and reliability—critical qualities for customer service applications where consistent adherence to policies is essential.