Gemini API: Antigravity Agent Gets Breaking Tool Update
Gemini CLIGoogle shipped antigravity-preview-09-2026, a new version of the Antigravity Agent available through the Gemini API's Managed Agents feature, replacing and deprecating antigravity-preview-05-2026. The update overhauls the agent's built-in tool schema: parameters switch from snake_case to PascalCase, file edits move from full-file rewrites to line-range replacements, and new search tools are added. Developers who only read output text from a remote sandbox just need to swap the model identifier string, but anyone parsing function-call steps or running tools locally must update their integration code. Google set an October 5, 2026 shutdown date for the older antigravity-preview-05-2026 model.
Key Takeaways
- antigravity-preview-09-2026 replaces the older antigravity-preview-05-2026 managed agent model in the Gemini API, with the previous version shutting down on October 5, 2026.
- The update reworks the agent's built-in tool schema, switching parameter names from snake_case to PascalCase.
- File edits move from full-file rewrites to line-range replacements, reducing token usage and the risk of unintended overwrites.
- Two new tools, find_by_name and grep_search, give the agent native file and code search instead of shelling out.
- Developers running the agent in a remote sandbox and reading only output text need only update the model identifier string.
- Developers running tools locally or parsing
function_callsteps must update their integration code before the October 5 shutdown.
Sources & Mentions
2 external resources covering this update
A New Version of the Antigravity Agent
On September 17, 2026, Google released antigravity-preview-09-2026, a new version of the Antigravity Agent available through the Gemini API's Managed Agents feature. The release replaces and deprecates the previous version, antigravity-preview-05-2026, which Google has scheduled to shut down on October 5, 2026, tracked on the deprecations page.
The Antigravity Agent lets developers spin up a Google-hosted agent through the Interactions API that can plan, write and execute code, browse the web, and manage files inside a sandbox, without developers needing to build their own agent orchestration infrastructure.
Breaking Changes to Tool Calling
The update is not a simple version bump: it changes how the agent's built-in tools work at the API level. Google's changelog draws a clear line between two groups of developers.
Developers who run the agent on a remote sandbox (environment: "remote") and read only the output_text or model_output steps face minimal disruption. For them, updating the model identifier string is the only change required.
Developers who run tools locally (local_environment) or who parse function_call steps directly are affected more significantly. The built-in tools themselves changed shape: parameters now use PascalCase instead of snake_case, and file edits use line-range replacements instead of full rewrites. File creation moves from write_file(path, content) to write_to_file(TargetFile, CodeContent, Overwrite, Description), and file editing from a full-rewrite write_file to replace_file_content(TargetFile, ...). Directory listing changes from list_files(path) to list_dir(DirectoryPath). Two new search tools were added where agents previously had to fall back on shell commands: find_by_name(SearchDirectory, Pattern, MaxDepth) and grep_search(SearchPath, Query, IsRegex). Shell execution via code_execution and web search via google_search are unchanged.
Why the Change Matters
Moving from full-file rewrites to line-range replacements reduces token consumption and lowers the risk of an agent clobbering code it did not intend to touch, since it edits a specific line range instead of resubmitting an entire file. Adding native find_by_name and grep_search tools also removes the agent's reliance on shelling out to external search utilities.
Migration Path
Google published an updated Antigravity Agent guide alongside the release and added the change to its deprecations page, giving developers roughly three weeks to migrate before the older model shuts down on October 5, 2026.