Gemini Antigravity Agent Migration: Update Tool Calls Without Silent Breakage

Last Updated on September 25, 2026 by Editorial Team Author(s): Anna Jey Originally published on Towards AI. Gemini Antigravity Agent Migration: Update Tool Calls Without Silent Breakage Gemini Antigravity Agent Migration A model-string change can be easy. A tool-contract change is a production migration. Here is how to move safely when an agent client reads, edits, or dispatches work locally. The dangerous kind of AI-agent upgrade is the one that looks boring in a release note. A team sees a new preview identifier, changes one configuration value, and deploys. The agent still returns a polished final message. Everyone relaxes. Then the first local run either ignores a file edit, sends malformed arguments to an internal executor, or records a successful job with no usable artifact. That is not a model-quality problem. It is a contract problem. Google’s September Antigravity Agent preview update is a useful reminder. The current Gemini API notes describe a new agent identifier and changes to built-in local-tool shapes: file operations move toward explicit, PascalCase parameters and line-range replacement rather than a broad full-file write. The managed agent itself can reason, run …

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