Researchers propose AgentRouter, a lightweight classifier that optimizes multi-step agentic workflows by routing individual trajectory steps to appropriate model tiers rather than using frontier models for every task. The system addresses the inefficiency of existing solutions that ignore varying subtask complexity within a single agent session.

  • AgentRouter uses a 12M parameter model with less than 5ms overhead per step on an A100 GPU to map steps to four tiers based on five features.
  • Trained on 50,000 annotated steps across planning, coding, research, and data analysis tasks, it achieves 72% cost reduction while retaining 97.3% of frontier-only quality.
  • Routing accuracy reaches 91% on minimal-complexity steps and 85% on efficient-tier steps, outperforming RouteLLM and FrugalGPT which achieved only 31% and 44% cost reductions respectively.

This approach significantly lowers inference costs for enterprise agentic systems by recognizing that different steps within a trajectory require different levels of model capability.