AEL: Agent Evolving Learning for Open-Ended Environments

TL;DR

The paper introduces Agent Evolving Learning (AEL), a framework enabling LLM agents to improve over open-ended tasks by learning how to utilize memory and reflection effectively, leading to superior performance.

Contribution

AEL is a novel two-timescale approach that combines learned retrieval policies and reflection-driven insights to enhance agent self-improvement in open-ended environments.

Findings

AEL outperforms existing self-improving methods and baselines on a financial portfolio benchmark.

Memory and reflection mechanisms together yield a 58% improvement over stateless agents.

Adding extra mechanisms degrades performance, highlighting the importance of effective self-diagnosis.

Abstract

LLM agents increasingly operate in open-ended environments spanning hundreds of sequential episodes, yet they remain largely stateless: each task is solved from scratch without converting past experience into better future behavior. The central obstacle is not \emph{what} to remember but \emph{how to use} what has been remembered, including which retrieval policy to apply, how to interpret prior outcomes, and when the current strategy itself must change. We introduce \emph{Agent Evolving Learning} (\ael{}), a two-timescale framework that addresses this obstacle. At the fast timescale, a Thompson Sampling bandit learns which memory retrieval policy to apply at each episode; at the slow timescale, LLM-driven reflection diagnoses failure patterns and injects causal insights into the agent's decision prompt, giving it an interpretive frame for the evidence it retrieves. On a sequential portfolio benchmark (10 sector-diverse tickers, 208 episodes, 5 random seeds), \ael{} achieves a Sharpe ratio of 2.13$\pm$0.47, outperforming five published self-improving methods and all non-LLM baselines while maintaining the lowest variance among all LLM-based approaches. A nine-variant ablation reveals a ``less is more'' pattern: memory and reflection together produce a 58\% cumulative improvement over the stateless baseline, yet every additional mechanism we test (planner evolution, per-tool selection, cold-start initialization, skill extraction, and three credit assignment methods) \emph{degrades} performance. This demonstrates that the bottleneck in agent self-improvement is \emph{self-diagnosing how to use} experience rather than adding architectural complexity. Code and data: https://github.com/WujiangXu/AEL.