---
title: "Tool usage in LLMs"
description: "Models can't browse, compute precisely, or act — until you give them tools. The ReAct pattern interleaves reasoning with tool calls (search, calculator, co"
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md_url: "https://fanout.sh/ai-engineering/lessons/tool-usage-in-llms.md"
access: "public"
---

# Tool usage in LLMs

Models can't browse, compute precisely, or act — until you give them tools. The ReAct pattern interleaves reasoning with tool calls (search, calculator, co

## Public overview

Models can't browse, compute precisely, or act — until you give them tools. The ReAct pattern interleaves reasoning with tool calls (search, calculator, code execution, APIs), and structured function-calling made it reliable enough to be the backbone of every agent framework.

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