Cortex Router · tau2-bench

Task-level routing across Qwen, GLM, and Kimi

A retrospective 100-task pilot of one routing decision for the full agent conversation, measured on task success and recorded model cost.

4 min read · R&D / ENG / FINOPS · 2026-08-02

Key takeaways

  • The operating point: On the 99-task common cohort, Cortex reaches 81% task success at $0.159 per completed conversation.
  • Point comparison: Against Kimi K3, it gives up 6 percentage points of success and uses 61% less mean cost.
  • Route mix: 5 Qwen3.7 Plus / 44 GLM-5.2 / 51 Kimi K3 across the 100-task pilot cohort.
Headline result

81% success at $0.159 per task

Against Kimi K3, the task-level router gives up 6 percentage points of task success and reduces mean agent cost by 61% on the 99-task common cohort. This is a point comparison, not an iso-cost result.

Router success
81%
80/99 tasks
Mean cost
$0.159
paired common cohort
Cost reduction
61%
versus Kimi K3
Tool compatibility matters. Qwen3.7 Plus encountered repeated empty-argument tool calls in this agent harness. Its pilot score should be read as system-level performance in this setup, not a model-only capability claim.
Performance & cost

Every point is a complete agent run

Task success is the tau2-bench reward. Cost includes the recorded model usage for the full conversation. The table shows each arm's available valid rows and makes differing denominators explicit.

Mean cost vs. task success

Provider logos identify every model and the Cortex router · scroll chart →

ConfigurationPassedSuccessCost / task
Qwen3.7 Plus20/10020%$0.103
GLM-5.283/10083%$0.307
Kimi K386/9987%$0.413
Cortex task-level router81/10081%$0.159
Operating profile

Per-task distributions, not cumulative curves

Stacked histograms show raw binned task counts across cost, turns, and token use. No smoothing. Hover a legend item or bar segment to isolate a series.

Agent cost

USD per task →

Stacked binned task counts by agent cost (x truncated at the 98th percentile). No smoothing. Each bar is a raw bin total.

  • Qwen3.7 Plus
  • GLM-5.2
  • Kimi K3
  • Cortex task-level router

Agent turns

Assistant turns per task →

Stacked binned task counts by assistant turns (x truncated at the 98th percentile). No smoothing. Each bar is a raw bin total.

  • Qwen3.7 Plus
  • GLM-5.2
  • Kimi K3
  • Cortex task-level router

Input tokens

Tokens per task →

Stacked binned task counts by input tokens (x truncated at the 98th percentile). No smoothing. Each bar is a raw bin total.

  • Qwen3.7 Plus
  • GLM-5.2
  • Kimi K3
  • Cortex task-level router

Output tokens

Tokens per task →

Stacked binned task counts by output tokens (x truncated at the 98th percentile). No smoothing. Each bar is a raw bin total.

  • Qwen3.7 Plus
  • GLM-5.2
  • Kimi K3
  • Cortex task-level router
Paired outcomes

Where routing changes the answer

The same 99 valid task IDs are compared between the router and Kimi K3.

Routing policy

One decision for the full conversation

Cortex scores the initial task prompt, chooses one model, and keeps that model for every turn. This avoids mid-conversation model changes and preserves prefix-cache locality.

Methodology

Retrospective, paired, and recomputable

This is a 100-task pilot from the tau2-bench base split. Cortex scores the initial task prompt, chooses one model, and keeps that model for every turn. Infrastructure failures are excluded from an arm's descriptive metric; headline comparisons use only task IDs valid in both the router and baseline arms.

Source data

Recompute every number

The export includes task ID, domain, arm, pass/fail, cost, turns, token counts, selected route, infrastructure status, and a claim map.

Chaos Labs Cortex · Router Analysistau2-bench 100-task pilot · 2026-08-02