Pushing ChatGPT's Structured Data Support To Its Limits. The GPT 3.5, 4 and 4 Turbo APIs all provide “function calling”—a misnamed feature that allows you to feed them a JSON schema and semi-guarantee that the output from the prompt will conform to that shape.
Max explores the potential of that feature in detail here, including some really clever applications of it to chain-of-thought style prompting.
He also mentions that it may have some application to preventing prompt injection attacks. I’ve been thinking about function calls as one of the most concerning potential targets of prompt injection, but Max is right in that there may be some limited applications of them that can help prevent certain subsets of attacks from taking place.
Recent articles
- Highlights from my appearance on the Data Renegades podcast with CL Kao and Dori Wilson - 26th November 2025
- Claude Opus 4.5, and why evaluating new LLMs is increasingly difficult - 24th November 2025
- sqlite-utils 4.0a1 has several (minor) backwards incompatible changes - 24th November 2025