AI Agents: How They Are Built
The shift underway is from writing prompts to designing the systems that prompt. These pages cover what an agent actually is, the patterns we use to build them, and the frameworks available.
7 articles · start with the first and read in order, or jump to what you need
- 1 · BeginnerGenerative AI, Agentic AI and AI AgentsThree terms separated by one variable: how much the system decides for itself. Getting them confused is why "agent" projects so often ship as chatbots.6 min read
- 2 · IntermediateA Learning Path for Building AI AgentsFive stages, in the order the work actually demands them. Opinionated, deliberately short, and honest about which stages most teams can skip.6 min read
- 3 · IntermediateLoop Engineering: Design the Loop, Not Every PromptA single prompt cannot fix a bug it has never seen run. Loop engineering builds the harness that lets an agent act, observe, reason and retry.6 min read
- 4 · IntermediateAnatomy of a Good Agent LoopFive things every well-built agent loop needs — and the specific failure each one prevents. If it cannot tell done from not-done, it is not a loop.7 min read
- 5 · AdvancedGraph Engineering: Coordinating Specialized AgentsWhen one agent is not enough: who does what, in what order, and what happens when a step fails. Graph engineering is how that gets specified.6 min read
- 6 · IntermediateLoops vs Graphs: How the Two Patterns NestOne agent iterating and many agents passing work are different things at different levels. Holding the distinction shortens architecture debates.5 min read
- 7 · AdvancedAI Agent Frameworks Compared: What Each One Is ForLangGraph, CrewAI, OpenAI Agents SDK, Claude Agent SDK, Google ADK, Microsoft Agent Framework and more — grouped by the problem each solves.10 min read
Common questions: AI Agents
What is an AI agent?
An AI agent is given a goal rather than a single instruction, and chooses and takes its own actions toward it — calling tools, observing the results and adjusting — until a stop condition is met.
What is the difference between generative AI and agentic AI?
Generative AI produces content when asked; every step is chosen by a person. Agentic describes how much a system decides and acts for itself. It is a spectrum, not a separate product category.
Which AI agent framework should I use?
Start from your language and the hard part of your problem. Graph frameworks such as LangGraph, Microsoft Agent Framework and Google ADK suit long-running, stateful work; LlamaIndex and Haystack suit retrieval-heavy work; a model vendor’s own SDK is the thinnest path on that vendor’s models. Many production systems use no framework at all.