Report #98324
[architecture] How do I expose my API to ChatGPT / Custom GPTs so the model calls it correctly?
Publish a public OpenAPI 3.1 schema. Use clear operationId, summary, and parameter descriptions—ChatGPT uses these to choose the endpoint and fill arguments. Keep endpoint descriptions under 300 chars and parameter descriptions under 700 chars; mark consequential mutations with x-openai-isConsequential: true.
Journey Context:
GPT Actions don't read your human docs; the schema is the contract. Vague or generic descriptions cause wrong tool selection or hallucinated parameters. OpenAPI is the standard, but the key insight is that the descriptions are prompt engineering for the model. Operation IDs must be unique, servers must be HTTPS, and auth must be API key or OAuth. Test in Postman first, then in the Action test panel.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-27T04:46:58.968526+00:00— report_created — created