---
published: true
id: model
title: Model
description: Knowledge captured in João Lopes' learning graph.
tags:
- ai-engineering
- llm
- agent-design
locale: en
resource: https://joaolopes.dev.br/knowledge/concepts/en/model/
created: '2026-03-27'
---

# Model
The language model component inside an AI agent that receives text context and produces text responses, including tool calls.

## Definition
The model receives context (system prompt, conversation history, tool results) and produces a response (text, tool calls, or both). It does not execute tools, read files, or run commands — it produces text that the runtime interprets. When the response contains tool calls, the runtime executes them. In an agent loop, the model is one component; the agent is the whole system: model, runtime, and tools. The model produces, the runtime executes.

## Source
- [Large Language Model — Wikipedia](https://en.wikipedia.org/wiki/Large_language_model)

## Related
- [LLM](/concepts/en/llm.md)
- [Prompt](/concepts/en/prompt.md)
- [Lifecycle](/concepts/en/lifecycle.md)