Antigravity Agent's new model breaks tool calls; migrate before Oct 5
Google's new Antigravity Agent renames every built-in tool, moves params to PascalCase and edits to line ranges; the old one stops serving in ~2 weeks.
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Every built-in tool got renamed
The new antigravity-preview-09-2026 swaps its whole tool surface: write_file() becomes write_to_file(), read_file() becomes view_file(), list_files() becomes list_dir(), and every parameter moves to PascalCase (TargetFile, CodeContent). Any agent or prompt hardcoding the old names or snake_case args silently breaks on the new model.
Edits are line-range now, plus native find and grep
File edits shift from full-file rewrites to targeted line-range replacements, so a change costs fewer tokens and is less likely to clobber a file. Two new built-ins, find_by_name and grep_search, replace the shell-command workarounds the old agent leaned on, so code search no longer needs a terminal round-trip.
The old model shuts down October 5
antigravity-preview-05-2026 stops serving on Oct 5, 2026, per Google's deprecations page, roughly two weeks out. If you pin that model ID in any script or CI job, switch to the 09-2026 model and update your tool schema now, or the agent goes dark.