ReAct pattern: Reason and act agent architecture

Google Cloud TechAbout 3 min readJan 29, 2026Watch original
THE SUMMARYAI-generated

Key Concepts

  • React Agent Architecture: A cyclical framework for AI agents focusing on thinking, acting, and observing.
  • Repetitive Loops: A common problem in AI agents where they get stuck repeating the same actions.
  • Tool Use: The agent’s ability to interact with external tools to gather information.
  • Memory Update: The agent’s process of incorporating observation results into its knowledge base.

The Problem of Repetitive Loops in AI Agents

The core issue addressed is the tendency of AI agents to become trapped in unproductive, repetitive loops. This occurs when an agent fails to effectively react to its environment and continues performing the same actions despite receiving no progress or relevant feedback. The video highlights this as a significant limitation in current AI agent design.

The React Agent Architecture: A Solution

The proposed solution is the “React Agent Architecture,” described as a “simple, powerful loop” designed to overcome the problem of repetitive behavior. This architecture consists of three core stages:

  1. Think: The agent engages in reasoning about the user’s request or current objective. This stage involves analyzing the situation and determining the next logical step. No specific reasoning techniques are detailed, but the emphasis is on deliberate thought before action.
  2. Act: Based on its reasoning, the agent takes an action. This action can take one of two forms:
    • Tool Use: The agent utilizes an external tool to obtain information relevant to the task. This is presented as a crucial component, allowing the agent to interact with the real world and gather data.
    • Answer Formation: The agent directly formulates a response or solution to the user’s request.
  3. Observe: The agent analyzes the result of its action. This observation is then used to update the agent’s memory, providing it with new information and context. This stage is critical for breaking repetitive loops, as it allows the agent to learn from its actions and adjust its strategy.

Illustrative Example: The Robot Chef

A concrete example is provided to illustrate the React Agent Architecture in action: a robot chef. The scenario unfolds as follows:

  • Think: The robot chef determines it needs eggs to fulfill a recipe.
  • Act: The robot chef opens the refrigerator.
  • Observe: The robot chef observes that there are no eggs in the refrigerator.
  • Think: Based on this observation, the robot chef reasons that it needs to add eggs to a shopping list.

This example demonstrates how the agent dynamically adjusts its plan based on observed results, preventing it from repeatedly opening an empty refrigerator.

Building and Implementing React Agents

The video concludes with a call to action, encouraging viewers to build their own React agents using Google Cloud. A link to a detailed blog post is provided in the first comment, offering further resources and guidance on implementation.

Synthesis

The React Agent Architecture offers a straightforward yet effective approach to building more robust and adaptable AI agents. By emphasizing a cyclical process of thinking, acting, and observing, it addresses the common problem of repetitive loops and enables agents to react intelligently to their environment. The architecture’s reliance on tool use and memory updates is key to its functionality, allowing agents to gather information and learn from their experiences. The provided example of the robot chef effectively illustrates the practical application of this framework.

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