LLM WORLD

Function calling in the OpenAI API

OpenAI · · Architecture

OpenAI shipped gpt-4-0613 and gpt-3.5-turbo-0613, fine-tuned to decide when a described function should be called and to emit a JSON object matching its signature.

Why it matters

Tool use stopped being a prompting trick and became an API primitive with a defined contract. Every agent framework after this date builds on structured tool calls rather than on parsing free text.

This is LLM World's historical reading, not a claim by OpenAI. The facts above and the sources below are what it rests on.

Sources

Record status: verified · confidence 90/100

Dateline 'June 13, 2023' read directly from a Wayback capture of OpenAI's own announcement taken two days later. openai.com blocks automated fetches, so the live URL was not read.