OS-Shepherd-9B
OS-Shepherd-9B is an open multimodal reward model for judging computer-use agent trajectories. Given a task instruction, screenshots, and the agent's reasoning and actions, it determines whether the task was completed and returns a reasoned SUCCESS or FAIL verdict.
It is fine-tuned from Qwen3.5-9B on OS-Shepherd-100K using SFT followed by GRPO, with the RL stage focused on reducing false-success judgments.
Usage
Use the canonical prompt and trajectory format from the OSReward repository. A recent Transformers, vLLM, or SGLang version with Qwen3.5 multimodal support is required.
This model is intended for trajectory evaluation, data filtering, and reward-model research. It is not a computer-control policy and may still miss fine-grained visual failures, especially on hard cases.
License
Apache License 2.0. See LICENSE.
Citation
@article{sun2026osreward,
title={OSReward: Instituting Standardized Evaluation for Cross-Platform Computer-Use Reward Models},
author={Sun, Qiushi and others},
journal={arXiv preprint arXiv:2607.28609},
year={2026}
}