Researchers propose AgentRouter, a lightweight classifier that optimizes multi-step agentic workflows by routing individual trajectory steps to appropriate model tiers rather than using a single frontier model for all tasks. The system addresses the inefficiency of enterprise systems that waste 60-80% of their inference budget on subtasks that smaller models can handle equally well.
- AgentRouter uses a 12M parameter classifier with less than 5ms overhead per step on an A100 GPU to map steps to four model tiers based on five extractable features.
- Trained on 50,000 annotated agent trajectory steps, it achieves a 72% cost reduction relative to frontier-only baselines while retaining 97.3% of the quality.
- The system demonstrates per-step routing accuracy of 91% on minimal-complexity steps and 85% on efficient-tier steps.
- It outperforms RouteLLM and FrugalGPT, which achieve only 31% and 44% cost reduction respectively, by accounting for trajectory-level quality dependencies that single-turn solutions miss.