Google Antigravity adds Claude Opus 5.5 and Sonnet 5.5 for enterprise coding

Google Cloud announced on October 20 that Claude Opus 5.5 and Claude Sonnet 5.5 are available to customers using its Antigravity coding tools. Administrators must enable the partner models before developers can choose them alongside Gemini models in the model picker. Google said the options work in Antigravity 2.0, the Antigravity command-line interface and IDE extensions for major editors.

The addition gives teams a way to compare different model families without leaving the same development environment. Google's announcement recommends using one model to implement a coding change and another to inspect it against tests and requirements, a suggested workflow rather than evidence that such reviews always improve outcomes. Antigravity also supports configurable subagents that can use lower-cost Gemini Flash models for routine tasks.

There is a billing caveat for enterprises: Google's announcement says third-party partner-model usage does not count against the pooled Gemini Enterprise monthly token quota. Instead, authorized customers pay through Google Cloud Billing, with overages enabled and administrators able to configure spend limits. Developers must use an updated Antigravity client and have their organization's model permissions in place.