STRUCTUREDAGENT: Planning with AND/OR Trees for Long-Horizon Web Tasks

arXiv:2603.05294 · cs.AI · Submitted 2026-03-05 · Read on arXiv

cs.AI

Submitted: 2026-03-05

Updated: 2026-09-19

License: http://creativecommons.org/licenses/by/4.0/

The gist: Existing LLM-based web agents struggle on complex, long-horizon tasks due to limited in-context memory, weak planning abilities, and greedy behaviors that lead to premature termination.

Terminology

Abstract

Existing LLM-based web agents struggle on complex, long-horizon tasks due to limited in-context memory, weak planning abilities, and greedy behaviors that lead to premature termination. To address these challenges, we propose, a hierarchical planning framework that interleaves planning and execution via dynamic trees. The framework separates structural planning from LLM-based reasoning, enabling principled error recovery through node repair, systematic exploration of alternatives via OR nodes, and modular plans that can facilitate human intervention. On WebArena (630 tasks), achieves a about 53% success rate vs. about 46% for AgentOccam, and on complex multi-constraint Amazon shopping tasks, gains reach 10% over the strongest baseline.

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