Paper Overview
Field: NLP Authors: Junhao Shen, Teng Zhang, Xiaoyan Zhao Published: 2025-05-09 arXiv: 2505.07240
Abstract
Large language model agents increasingly rely on external skills to solve complex tasks, where skills act as modular units that extend their capabilities beyond what parametric memory alone supports. Existing methods assume external skills either accumulate as persistent guidance or are internalized into the policy, eventually leading to zero-skill inference. The authors argue this assumption is overly restrictive: with limited parametric capacity and uneven marginal contribution across skills, the optimal active skill set is non-monotonic and task- and stage-dependent.
The SLIM Framework
SLIM (dynamic Skill LIfecycle Management) treats the active external skill set as a dynamic optimization variable jointly updated with policy learning in agentic reinforcement learning:
- Contribution estimation: Leave-one-skill validation estimates the marginal external contribution of each active skill.
- Retain: Keep high-value skills.
- Retire: Remove skills whose contribution becomes negligible after sufficient exposure.
- Expand: Grow the skill library when persistent failures reveal capability coverage gaps.
- SLIM outperforms the best baseline by an average of 7.1 percentage points on ALFWorld and SearchQA.
- Policy learning and external skill retention are not mutually exclusive: some skills are absorbed into the policy while others continue to provide external value, supporting SLIM as a more general paradigm for skill-based agentic RL.