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Chapter 9 Agentic AI — Building Autonomous Intelligent Systems

What Is Agentic AI? — From Chatbots to Autonomous Systems

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What Is Agentic AI? — From Chatbots to Autonomous Systems

For most of AI's history, systems were reactive — they answered a question, then stopped. Agentic AI changes that contract entirely. An agentic AI system perceives its environment, reasons about goals, plans multi-step strategies, takes real-world actions, and adapts based on results — all with minimal human hand-holding.

The Intelligence Spectrum

Simple Chatbot → RAG System → Tool-Using LLM → Agentic AI → Fully Autonomous System
     |                |              |                |                |
 Q&A only       Knowledge +     External tools    Multi-step       Self-directed
                 retrieval       + reasoning       planning         goal pursuit

A chatbot gives you an answer. An agentic AI books the flight, writes the confirmation email, and updates your calendar.

Four Core Capabilities of Agentic AI

Capability Description Example
Perception Read environment state Browse web, read files, observe APIs
Reasoning Think through what to do Chain-of-thought, planning, reflection
Action Execute in the real world Call APIs, write code, send messages
Memory Retain context over time Remember past steps, past conversations

The ReAct Framework — Reasoning + Acting

The most influential pattern for agentic AI is ReAct, which interleaves thinking and doing:

Thought: I need to find the current price of NVDA stock.
Action: search_web("NVDA stock price today")
Observation: NVDA is trading at $134.50 as of market close.
Thought: Now I have the price. I can calculate the portfolio value.
Action: calculate(134.50 * 1000)
Observation: 134500
Final Answer: Your 1,000 NVDA shares are worth $134,500.

This loop — Observe → Think → Act → Observe — repeats until the agent reaches its goal or decides it cannot.

Agentic AI vs Traditional AI

Aspect Traditional AI Agentic AI
Interaction Single query → response Multi-step autonomous loop
Tools None Web, code, APIs, databases
Memory Stateless Short + long-term memory
Planning No Yes — decompose and sequence
Human role Drives every step Sets goal, reviews result

Real-World Agentic Systems in 2026

  • Devin — autonomous software engineering agent (searches docs, writes code, runs tests, fixes bugs)
  • Claude Computer Use — operates a computer like a human (clicks, types, navigates)
  • AutoGPT / BabyAGI — early open-source agents that demonstrated the agentic loop concept
  • OpenAI Operator — browser-operating agent for real-world web tasks

Why Agentic AI Is a Paradigm Shift

Traditional AI scales with better models. Agentic AI scales with better systems — more tools, better memory, smarter planning. A smaller model with excellent tool use often outperforms a larger model without it.

Key Takeaways

  • Agentic AI = perceive + reason + act + remember, in a loop
  • The ReAct pattern (Reason + Act) is the foundational loop for most agents
  • Tool use is what gives AI "hands" to affect the real world
  • Memory is what gives AI continuity across long tasks
  • The shift from "AI as oracle" to "AI as operator" is the defining trend of 2026