Agent Model Router Test: 91% Cost Drop, 57% Task Success Rate

kleffew94 · x · 2026-08-13

As LLM iterations accelerate, choosing the right model becomes complex. BlockRun released a benchmark report for AI Agent model routing, proposing a "constraint-first" routing strategy. Instead of relying on an LLM to guess, it filters out unqualified models based on request signals and ranks only the qualified candidates, balancing cost and success.

The experiment compares the new router, the old router, and a fixed Opus 5 baseline:

The author admits that while the results show high cost-effectiveness, the new router's p95 latency remains high, and statistical non-inferiority to the flagship model is not yet fully established.

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