SaFeR-ToolKit: Structured Reasoning via Virtual Tool Calling for Multimodal Safety

Zixuan Xu, Tiancheng He, Huahui Yi, Kun Wang, Xi Chen, Gongli Xi, Qiankun Li, Kang Li, Yang Liu, Zhigang Zeng


Abstract
Vision–language models remain susceptible to multimodal jailbreaks and over-refusal because safety hinges on both visual evidence and user intent, while many alignment pipelines supervise only the final response. To address this, we present SaFeR-ToolKit, which formalizes safety decision-making as an inspectable protocol: during offline data synthesis, a planner specifies a persona, a **Perception**→**Reasoning**→**Decision** tool set, and a constrained transition graph, while a responder emits a typed key–value tool trace before the final answer. To learn this protocol, we train a single policy with a three-stage curriculum (SFT→DPO→GRPO), where GRPO directly supervises tool usage beyond answer-level feedback. We contribute (**I**) the first tool-based safety reasoning dataset of 30,654 training entries (SFT 6k, DPO 18.6k, GRPO 6k) plus 1k held-out evaluation, and (**II**) experiments on Qwen2.5-VL showing large gains in Safety/Helpfulness/Reasoning Rigor on 3B (29.39/45.04/4.98 → 84.40/71.13/78.87) and 7B (53.21/52.92/19.26 → 86.34/80.79/85.34), while preserving general capabilities (3B: 58.67 → 59.21; 7B: 66.39 → 66.81). Code: [https://github.com/Duebassx/SafeR_Toolkit](https://github.com/Duebassx/SafeR_Toolkit).
Anthology ID:
2026.aacl-long.233
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
5223–5250
Language:
URL:
https://aclanthology.org/2026.aacl-long.233/
DOI:
Bibkey:
Cite (ACL):
Zixuan Xu, Tiancheng He, Huahui Yi, Kun Wang, Xi Chen, Gongli Xi, Qiankun Li, Kang Li, Yang Liu, and Zhigang Zeng. 2026. SaFeR-ToolKit: Structured Reasoning via Virtual Tool Calling for Multimodal Safety. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 5223–5250, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
SaFeR-ToolKit: Structured Reasoning via Virtual Tool Calling for Multimodal Safety (Xu et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-long.233.pdf