Does Chain-of-Thought Reasoning Help Mobile GUI Agents? An Empirical Study
Paper · 2026 · Li Zhang, Longxi Gao and Mengwei Xu
Summary
The paper asks whether vision-language models with built-in chain-of-thought reasoning make better mobile GUI agents, meaning systems that operate a smartphone from natural-language instructions. The authors compared six base and reasoning model pairs: the commercial Gemini 2.0 Flash and Claude 3.7 Sonnet, and the open-source AgentCPM-GUI-8B, GLM-4.5V, Qwen3-VL-4B and Qwen3-VL-8B. They tested several agent configurations on two static benchmarks, ScreenSpot and AndroidControl, and on the interactive AndroidWorld environment.
Overall, reasoning added little and sometimes lowered accuracy. The base and reasoning variants also failed on different tasks, so the gains and losses largely cancelled out. Manual error analysis traced the problems to two sources:
- Benchmark weaknesses: ambiguous instructions, and static data that accepts only one correct action.
- Model weaknesses: misreading screen details, and final answers that contradict the preceding reasoning.
Reasoning also multiplied output tokens, which raised latency and cost. The study matters because it questions the assumption that reasoning is always worth enabling. It argues for interactive evaluation, GUI-specific training, and adaptive or budgeted reasoning.
Key points
- AndroidControl: Gemini Thinking reached 54.4% action accuracy, only 0.8 points above its base model. On ScreenSpot grounding, only Claude Thinking with normalized center-point output improved; other setups lost up to 29.7%.
- AndroidWorld (116 tasks): Claude Thinking with set-of-mark prompting completed 64.7% of tasks, 6.3 points above its base model. The Gemini and Qwen3-VL reasoning variants performed slightly worse than their base versions.
- Different failures: Gemini Thinking failed 36% (ScreenSpot), 9% (AndroidControl) and 12% (AndroidWorld) of the tasks its base model solved. It also solved up to 10% of the tasks the base model missed.
- Cost: Output tokens rose by 3.11× to 14.78×. On ScreenSpot, the average grew from 37.6 to 238.5 tokens.
- Reasoning budget: In a budget experiment with GLM-4.6V on AndroidControl, a 128-token budget worked best, adding about 1.23 points of action accuracy over no reasoning. Larger budgets did not help further and generally reduced accuracy.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 18,614 worksComputer Vision and Pattern Recognition · 3,486 worksInformation Systems · 1,730 worksHuman-Computer Interaction · 160 works
🧭 Topics 1Research subjects and languages the work is about.Reasoning · 1,685 works
Cite
Cite as Li Zhang, Longxi Gao and Mengwei Xu. 2026. Does Chain-of-Thought Reasoning Help Mobile GUI Agents? An Empirical Study. Findings of the Association for Computational Linguistics: ACL 2026.
@inproceedings{zhang2026does,
title = {{Does Chain-of-Thought Reasoning Help Mobile GUI Agents? An Empirical Study}},
author = {Li Zhang, Longxi Gao and Mengwei Xu},
booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
year = {2026},
doi = {10.18653/v1/2026.findings-acl.392},
url = {https://doi.org/10.18653/v1/2026.findings-acl.392}
}References
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