Instruction granularity is an important yet poorly controlled variable in language-guided embodied AI. Existing benchmarks typically pair each task with a single static instruction, making it difficult to study how agent behavior changes when the same task is described at different levels of detail. We introduce Mini-BEHAVIOR-Gran, a new benchmark for controlled studies of instruction granularity that extends Mini-BEHAVIOR with multiple instruction variants per task, ranging from high-level goal descriptions to step-by-step guidance. Using this benchmark, we compare four candidate metrics for cross-task granularity quantification: token count, entity count, action-verb count, and planning-width, and find that width correlates most consistently with agent performance. Using width to organize training and evaluation further reveals a non-monotonic U-shaped relationship between instruction granularity and performance, with peaks at both fine and coarse extremes. Further analysis suggests that the coarse-granularity performance rebound is associated with shallow grounding, where agents learn vision-dominant policies.
@article{arxiv.2604.17019,
title = {Mini-BEHAVIOR-Gran: Revealing U-Shaped Effects of Instruction Granularity on Language-Guided Embodied Agents},
author = {Sukai Huang and Chenyuan Zhang and Fucai Ke and Zhixi Cai and Gholamreza Haffari and Lizhen Qu and Hamid Rezatofighi},
journal= {arXiv preprint arXiv:2604.17019},
year = {2026}
}
Comments
23 pages, Keywords: Language Grounding, Language Granularity, Instruction Following Agent, Width-based Planning Research Area: Multimodality and Language Grounding to Vision, Robotics and Beyond Research Area Keywords: vision language navigation, multimodality, neurosymbolic approaches