# Build an AI Agent (From Scratch)

DevFeed: [Build an AI Agent (From Scratch)](<https://devfeed.tech/articles/build-an-ai-agent-from-scratch-18918.md>)

Original publisher: [Read original article](<https://blog.frankel.ch/building-ai-agent-from-scratch/>)

Author: Nicolas Fränkel

Published: 2026-09-06T00:00:00Z

Content type: opinion

Language: en

Sources: [Nicolas Fränkel](<https://devfeed.tech/sources/nicolas-frankel.md>)

Topics: [AI Agent](<https://devfeed.tech/topics/ai-agent.md>), [Large Language Model](<https://devfeed.tech/topics/llm.md>), [Model Context Protocol (MCP)](<https://devfeed.tech/topics/model-context-protocol-mcp.md>), [Retrieval Augmented Generation (RAG)](<https://devfeed.tech/topics/retrieval-augmented-generation-rag.md>), [Multi Agent Systems](<https://devfeed.tech/topics/multi-agent-systems.md>)

Tags: [ai](<https://devfeed.tech/tags/ai.md>), [ai-agent](<https://devfeed.tech/tags/ai-agent.md>), [ai-agents](<https://devfeed.tech/tags/ai-agents.md>), [book](<https://devfeed.tech/tags/book.md>), [claude-code](<https://devfeed.tech/tags/claude-code.md>), [coding-assistant](<https://devfeed.tech/tags/coding-assistant.md>), [genealogy](<https://devfeed.tech/tags/genealogy.md>), [llm](<https://devfeed.tech/tags/llm.md>), [llms](<https://devfeed.tech/tags/llms.md>), [mcp](<https://devfeed.tech/tags/mcp.md>), [multi-agent-systems](<https://devfeed.tech/tags/multi-agent-systems.md>), [rag](<https://devfeed.tech/tags/rag.md>), [review](<https://devfeed.tech/tags/review.md>)

## AI overview

A review of Build an AI Agent (From Scratch) by Jungjun Hur and Younghee Song describes the book's coverage of LLM agents, tool use, ReAct agents, RAG, memory, planning, code execution, multi-agent systems, and agent evaluation. The reviewer considers it a fundamental introduction, while wishing the evaluation chapter were more developed.

## Source excerpt

Facts 10 chapters$29.29 (at the time of this writing)315 pages Chapters Building your first LLM agentWhat is an AI agent?