| Abstract: |
Large language models are increasingly used not only as text generators but also as the core reasoning component of autonomous and semi-autonomous agent systems. When coupled with memory, planning, tool use, and interaction with external environments, these systems can address tasks that are difficult to solve through single-turn prompting alone. This paper presents a survey of large language model-based autonomous agents, with emphasis on architectural design, coordination strategies, evaluation methodology, failure recovery, and practical system selection. The survey organizes prior work along three dimensions: agent cardinality, memory design, and planning style. It also compares representative systems such as ReAct, Reflexion, AutoGen, MetaGPT, CrewAI, LangGraph, DyLAN, and ToolMaker, while reviewing application domains including software engineering, research support, healthcare, education, finance, and customer service. In addition, it synthesizes current evaluation practices across AgentBench, SWE-bench, SWE-bench Verified, GAIA, and WebArena, highlighting the extent to which scaffold design influences reported performance. The survey also examines failure propagation, state synchronization, retry behavior, benchmark limitations, and reproducibility factors that influence agent-system evaluation. The objective is to provide a systems-oriented synthesis for researchers and a practical design reference for practitioners developing deployable agent systems. |