---
title: "Agent foundations"
id: "foundations"
pass: "Pass 1: Agent Foundations"
canonical_url: "https://renatomignone.github.io/From-LLMs-to-Secure-Agents/foundations/"
total_chapters: 5
---

# Agent foundations

> **Section Overview:** Define agentic systems by observable behavior and system structure, not by product labels.
> **Pass:** Pass 1: Agent Foundations · **Published chapters:** 5

## Learning Outcomes
The reader can define an agent, trace a perception-decision-action loop, distinguish deterministic workflows from model-directed agents, identify autonomy levels, and state termination conditions.

## Published chapters
- [What is an agent](https://renatomignone.github.io/From-LLMs-to-Secure-Agents/foundations/01-what-is-an-agent/) - Defines an agent as an autonomous software system combining a reasoning model with tools, environment observations, and goal-directed control loops.
- [The agent loop](https://renatomignone.github.io/From-LLMs-to-Secure-Agents/foundations/02-the-agent-loop/) - Explains the internal mechanics of the agent execution loop, detailing how models perceive environment feedback, decide actions, and execute tools across iterative turns.
- [Workflows versus agents](https://renatomignone.github.io/From-LLMs-to-Secure-Agents/foundations/03-workflows-versus-agents/) - Compares deterministic code-orchestrated workflows with model-directed autonomous agents, establishing clear criteria for when each architectural pattern should be used.
- [Goals, policies, environments, and autonomy](https://renatomignone.github.io/From-LLMs-to-Secure-Agents/foundations/04-goals-policies-environments-and-autonomy/) - Details how agent goals, operational policies, environment characteristics, and autonomy levels interact to govern agent behavior and safety.
- [Run lifecycle and termination](https://renatomignone.github.io/From-LLMs-to-Secure-Agents/foundations/05-run-lifecycle-and-termination/) - Defines the complete lifecycle of an agent run from initialization to termination, detailing execution states, pause mechanisms, and multi-layered stopping conditions.