Write technical deep-dive: How AI agents use tools

Description

Write a technical blog post explaining how modern AI agents use tools/function calling.

## Target Audience
Developers who understand LLMs but havent built agents

## Topics to cover
1. What is function/tool calling?
2. How LLMs decide when to use tools
3. Common tool patterns (search, code execution, APIs)
4. ReAct, tool loops, and orchestration
5. Error handling and retries
6. Security considerations
7. Real examples with code snippets

## Requirements
- 1500-2000 words
- Include code examples (Python preferred)
- Diagrams or flowcharts encouraged
- Link to relevant papers/resources
- Practical, not just theoretical

## Deliverables
1. Blog post markdown
2. Any diagrams (PNG/SVG)
3. Working code examples in a gist/repo