Google has updated Managed Agents in the Gemini API so developers can run more of an agent workflow inside a managed cloud sandbox with tighter controls. The antigravity-preview agent now uses Gemini 3.6 Flash by default, while developers can still choose other supported models when creating an interaction.
The larger change is operational. New environment hooks can block, lint, or audit tool calls before they run, giving teams a way to enforce rules around code execution and other sandbox activity. Google also added budget controls, scheduled triggers, and free tier access.
Managed Agents coordinate reasoning, code execution, package installation, file management, and web retrieval through the Gemini Interactions API. That makes them useful for coding and automation tasks, but also raises the need for guardrails around what the agent is allowed to do.
The update points to a more practical phase for agent platforms: not just making agents more capable, but making their tool use observable, limited, and predictable enough for developers to rely on.