The builder’s guide to GPT‑5.6

OpenAI's programmatic tool calling lets GPT-5.6 write a JavaScript program that calls tools and handles their intermediate results, instead of the model reading every result itself. According to OpenAI's documentation, the program runs in a hosted runtime, can call tools in parallel, and can filter or aggregate data. The model then receives the program's final output.

OpenAI says this can reduce the intermediate tool output added to model context, but the effect depends on the task and tool responses. It suggests the approach for stages with predictable control flow, where code can return a smaller structured result, and direct calls when each result needs fresh model judgment or an action needs approval.