# Chapter 6: Planning and Reasoning

> 🧠 *"A truly intelligent Agent doesn't just execute commands — it can independently plan, reason, and complete complex tasks."*

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## Chapter Overview

This chapter dives deep into the Agent's "brain" — the planning and reasoning system. If tool use gives an Agent "hands" and the memory system gives it "recollection", then planning and reasoning give it the power to "think". From the ReAct framework to task decomposition and self-reflection mechanisms, this chapter helps you build Agents capable of handling complex, multi-step problems.

## Chapter Goals

After completing this chapter, you will be able to:

- ✅ Understand the core mechanisms of Agent reasoning (ReAct, OODA, Plan-and-Execute)
- ✅ Implement a ReAct Agent from scratch and understand the "Think-Act-Observe" loop
- ✅ Master task decomposition strategies to break complex problems into executable subtasks
- ✅ Implement reflection and self-correction mechanisms so Agents can learn from mistakes
- ✅ Build a research assistant Agent that integrates planning and reasoning

## Chapter Structure

| Section | Content | Difficulty |
|---------|---------|-----------|
| 6.1 How Do Agents "Think"? | Reasoning mechanisms and cognitive frameworks | ⭐⭐ |
| 6.2 ReAct Framework | The classic implementation of Reasoning + Acting | ⭐⭐⭐ |
| 6.3 Task Decomposition | Strategies for breaking down complex problems | ⭐⭐⭐ |
| 6.4 Reflection and Self-Correction | Making Agents self-improve | ⭐⭐⭐ |
| 6.5 Practice: Research Assistant Agent | Comprehensive application | ⭐⭐⭐⭐ |

## ⏱️ Estimated Study Time

Approximately **90–120 minutes** (including hands-on exercises)

## 💡 Prerequisites

- Completed Chapter 4 (Tool Use) and Chapter 5 (Memory Systems)
- Familiar with Python function definitions and dictionary operations
- Basic experience with LLM API calls

## 🔗 Learning Path

> **Prerequisites**: [Chapter 4: Tool Use](../chapter_tools/README.md), [Chapter 5: Memory Systems](../chapter_memory/README.md)
>
> **Recommended Next Steps**:
> - 👉 [Chapter 7: RAG](../chapter_rag/README.md) — Connect Agents to external knowledge
> - 👉 [Chapter 12: LangChain](../chapter_langchain/README.md) — Efficiently implement ReAct Agents with a framework
> - 👉 [Chapter 13: LangGraph](../chapter_langgraph/README.md) — Implement complex reasoning flows with graph structures

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*Next: [6.1 How Do Agents "Think"?](./01_how_agents_think.md)*