Complete Tutorial

Custom Tool Building

Extend any AI agent with custom tools using LLM function calling. Build a database reader, a Stripe API client, and a compound agent that combines both.

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Everything you need to build custom tools for your AI agents. From SQLite database queries to Stripe API integration.

$9.99

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What You'll Learn Inside

🗄️

Database Reader

Query SQLite databases using natural language. Turn stakeholder questions into SQL without writing a single query.

💳

Stripe Integration

Check subscription status, look up customers, and pull invoices in real time through natural language.

🔗

Compound Agents

Chain multiple tools together. Find churn-risk customers and their payment status in one sentence.

🚀

Production Ready

Wrap your agent in FastAPI, add error handling, retry logic, and schema reflection for real-world deployment.

What's Inside

1

How LLM Function Calling Works

The three-party dance: user, LLM, and your code. No secrets exposed.
2

Project Setup

Minimal prerequisites: Python 3.10+, an API key, and 30 minutes. No Docker, no cloud.
3

Tool 1: The Database Reader

Build a SQLite query tool with safety guards and schema reflection.
4

Tool 2: The Stripe API Client

Three Stripe tools: customer lookup, subscription status, and invoice retrieval.
5

Tool 3: The Compound Agent

Combine database and Stripe tools to identify churn-risk customers autonomously.
6

Error Handling & Edge Cases

Hallucinated tool names, API timeouts, invalid SQL, and schema drift.
7

Deployment & Next Steps

Wrap in FastAPI, add nginx, scale to Slack, GitHub, and more.
8

Full Code Appendix

Complete, copy-pasteable code for all tools and the main agent loop.

Is This For You?

This guide is built for anyone hitting the wall with conversational-only agents.

🤖 Solo Agent Users

Hit the wall where one agent can't handle complex tasks. Time to build a tool ecosystem.

👨‍💻 Developers & Builders

Want to connect AI agents to real databases and APIs without security nightmares.

🏭 Automation Engineers

Need production-grade tool pipelines that handle research, billing, and compliance.

💰 Budget-Minded

Local tools on Ollama cost pennies. No expensive API calls for every database lookup.