Meta Paper: Training Agents to Decide When to Use Memory via RL

rohanpaul_ai · x · 2026-08-24

Meta introduces EvoHarness-RL, a novel method addressing the issue of long-horizon agents forgetting state due to task length.

Key Insight: Simply adding memory and tools is insufficient; the critical breakthrough is training the agent when it is worth using external state. EvoHarness-RL uses Reinforcement Learning to teach the policy model to balance between "calling external state (Belief, Progress, Experience)" and "saving interaction steps."

Performance:

On ALFWorld tasks, Qwen3-8B with ReAct scored only 47.9%. With EvoHarness-RL, it surged to 96.9% (seen tasks) and 86.6% (unseen tasks).
During training, as success rates rose, the frequency of external state calls dropped to approximately 1 per episode. This indicates routine behavior is internalized into the model weights, leaving external memory access for critical moments.

Takeaway: Agent builders should train policies to decide when to consult and update memory rather than hard-coding constant access.

Original post →

Meta Paper: Training Agents to Decide When to Use Memory via RL

More from coding & agent