GPT-5.6 API Adds Tool Calling, Multi-Agent Capabilities, New Models.

@simonw· July 9, 2026 View original

Summary

OpenAI's GPT-5.6 introduces significant API enhancements, including programmatic tool calling and multi-agent functionalities. The update also features three new models and six reasoning levels, metaphorically represented by "pelicans."

OpenAI has unveiled GPT-5.6, bringing substantial updates to its API. Key new features include programmatic tool calling, which allows the model to interact with external tools and services, and multi-agent capabilities, enabling more complex, collaborative AI workflows. The release also introduces three new models and categorizes reasoning into six distinct levels, a concept illustrated internally with a "pelican" metaphor. These advancements aim to expand the practical applications and sophistication of AI systems.

Why it matters

These API additions empower developers to build more dynamic and integrated AI applications, automating complex tasks and enabling sophisticated multi-step reasoning.

How to implement this in your domain

  1. 1Explore the new API documentation for GPT-5.6 to understand programmatic tool calling.
  2. 2Design and prototype multi-agent systems for complex workflows like customer support or data analysis.
  3. 3Integrate new models into existing applications to test performance improvements.
  4. 4Develop custom tools that GPT-5.6 can call to extend its functionality.

Who benefits

Software DevelopmentAI/MLCustomer ServiceAutomationData Science

Key takeaways

  • GPT-5.6 introduces programmatic tool calling for external interactions.
  • Multi-agent capabilities enable more complex AI workflows.
  • Three new models and six reasoning levels are part of the update.
  • Developers can build more dynamic and integrated AI applications.

Original post by @simonw

"Notes on GPT-5.6, which includes some interesting new additions to the API (programmatic tool calling and multi-agent in particular) - plus 18 pelicans for the 6 reasoning levels and 3 new models: ... and if you want to see some of OpenAI's own pelicans they featured a 3D pelican…"

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