EC²-Bench benchmarks edge-cloud collaboration for long-horizon agents
Cost and privacy trade-offs in agent execution do not move together — once task completion converges, strategy choice is mostly a privacy decision, and the best-scoring setup is also the most exposed. Teams deploying on-device agents can pick a collaboration mode based on edge model size: route execution to the cloud for small models, use cloud advisory for 9B-class ones. The comparison against Tsinghua-affiliated GLM-5.3 makes the findings directly applicable to Chinese open-source model stacks.
OpenBMB and Tsinghua researchers introduced EC²-Bench, a benchmark evaluating four edge-cloud collaboration strategies across 128 executable agent tasks. With Qwen3.5-9B on-device and GLM-5.3 in the cloud, the best collaboration reached 60.46 completion versus 39.12 edge-only, at US$8.73 versus US$56.42 for cloud-only. On Qwen3.7-Plus, strategy gaps in task completion shrank to 3.67 points, yet privacy exposure varied by 66.23 percentage points, with the top-performing strategy leaking the most. The optimal mode flipped with edge capability: 2B models scored 39.97 with per-step cloud routing versus 15.86 with self-delegation, while 9B models did best when the cloud only advised.
When should the cloud execute for the edge agent, and when should it just advise?
We present a systematic study of edge-cloud collaboration in long-horizon agent execution. Using EC²-Bench, we evaluate four collaboration strategies across 128 executable tasks, jointly measuring task completion, resource cost, and privacy exposure. Here are three key findings:
1️⃣ Small cloud budget, big gains.(cost-efficiency). With Qwen3.5-9B on-device and GLM-5.3 in the cloud, edge-only scores 39.12; the best collaboration reaches 60.46 — about 73% of cloud-only (82.70) — at only $8.73, roughly 15% of cloud-only's $56.42. 2️⃣ Performance converges, privacy doesn't. On Qwen3.7-Plus, best collaboration hits 76.84 vs 82.70 cloud-only; strategy gaps shrink to just 3.67 completion points, yet privacy exposure spans 66.23 percentage points — and the best-performing strategy leaks the most. 3️⃣ The mode flips with edge capability. Weak edges do best with an external router that lets the cloud execute (2B: Per-step Routing 39.97 vs self-delegation 15.86); stronger edges do best when the cloud only advises (9B Cloud Advisory 60.46). Further experiments highlight two abilities that matter for effective self-directed collaboration: knowing when to ask for help, and actually acting on the cloud's advice.
📄 Paper: https://t.co/ESc7nA1Aeu 🌐 Project: https://t.co/J1A3ZjtgCj 💻 Code: https://t.co/xjAuYnCDT1
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