Hook Types

In Claude Code, you can configure three distinct handler types for your hooks—Command, Prompt, and Agent—depending on whether you need a script, an AI "judgement call," or a specialized researcher to validate actions. Command hooks (type: "command") are deterministic shell scripts that execute standard commands (like npm run lint) and use exit codes to either approve the action or block it with an error message. Prompt hooks (type: "prompt") use a lightweight Claude model for single-turn evaluation, where the model analyzes the context (e.g., "Is this commit message descriptive?") and returns a simple JSON yes/no decision. Finally, Agent hooks (type: "agent") are the most sophisticated, spawning a multi-turn subagent with tool access (like Read or Grep) to conduct deep, autonomous verification before deciding if the main agent should proceed.