Google publishes Gemini 4 Carbon developer guide, lists API changes and pricing

Google publishes a developer guide for Gemini 4 Carbon covering API changes, decoding of up to 1M tokens, and multi-agent patterns.

Google AI Studio says the guide covers how to choose between Carbon and Gemini 4 Argon. Carbon has a unified 1M-token context window and thinking_level settings of low, medium, and high. Introductory pricing is $2 input and $10 output per 1M tokens through November 30, 2026, rising to $4 and $20 from December 1, with 95% off cached input tokens. Access is through the paid Gemini API tier and for Google AI Ultra subscribers in AI Studio and Google Antigravity. Scientists and researchers can apply for six months of free access in Antigravity, and cybersecurity defenders can apply to the Fairwind Program.

Philipp Schmid, who works on Google's developer relations, says upgrading from Argon requires only changing the model ID to gemini-4-carbon and that he uses medium thinking_level for most tasks. He also describes a /swarm preview in Antigravity that creates a multi-agent team communicating through a message board.