Programmatic Tool Calling: GPT-5.6 Writes JavaScript to Orchestrate Its Own Tool Calls

OpenAI API Docs·high signal

The Responses API now ships Programmatic Tool Calling, where the model writes and runs JavaScript that coordinates tools — calling them in parallel, using loops and conditionals, and holding intermediate results in a hosted V8 runtime rather than passing every tool response back through the model. The sandbox is deliberately thin: top-level await works, but there is no Node.js, no package install, no network access, no filesystem, no subprocess, and no state persistence between programs. This is the single most builder-actionable piece of the GPT-5.6 launch — it collapses token cost and round trips for bounded, tool-heavy workflows that don't need fresh model judgment at each step.