Google has added a control layer to the managed agents in its Gemini API, letting developers run their own code before and after every tool call an agent makes inside its cloud sandbox, and cancel the call outright. The same update makes Gemini 3.6 Flash the default model behind the agent, caps how many tokens a single run can consume, and opens the feature to projects with no billing attached. Managed agents are Google’s hosted version of the agent loop, the same pattern behind the assistants…