GeminiCLI/Hook

• Hooks reference – Gemini CLI

  • GeminiCLI's implementation of AI/Agent/Hook: scripts run at points in the agentic loop, synchronously — the CLI waits for every matching hook before continuing. Communication is JSON over stdin and stdout, and a stray print before the JSON breaks parsing.
  • Events: BeforeTool, AfterTool, BeforeAgent, AfterAgent, BeforeModel, BeforeToolSelection, AfterModel, SessionStart, SessionEnd, Notification, PreCompress.
  • That naming is the clearest evidence that hook events are not standardized. Gemini's BeforeTool is Claude/Code/Hook's PreToolUse and CursorAI/Hook's preToolUse, and PreCompress is what the others call compaction — three hosts, three vocabularies for the same moment.
  • Configured in settings.json under a hooks object, one array of definitions per event. A GeminiCLI/Extension ships them as hooks/hooks.json. Conceptual overview: Gemini CLI hooks.