Connecting Custom GPTs to Internal APIs Using OpenAPI 3.1 Specs

Empower custom ChatGPT instances to query SQL databases, send Slack messages, and trigger GitHub actions securely.

Prerequisites

OpenAPI / Swagger understanding
A public HTTPS API endpoint

Step 1: Step 1: Writing Minimalist OpenAPI Schemas for LLM Readability

Remove unnecessary verbose error models to keep schema token overhead small while writing explicit description parameters for every field.

Step 2: Step 2: Configuring OAuth2 Bearer Authentication

Set up authorization endpoints so ChatGPT users authenticate securely without hardcoding static API secrets.