Hooks and Advanced Workflow Automation

Hooks in Claude Code are special triggers that let you run your commands at specific moments in Claude’s workflow. Normally, when you ask Claude to do something (such as read a file or run a command), Claude decides which tool to use and executes it. With hooks, you can intercept this process to perform actions before a tool runs or after a tool finishes.

This gives you more control over what Claude can do and lets you automate routine tasks. Think of hooks as event listeners or guardrails: you can automatically check or modify what Claude is about to do, or clean up and enhance what Claude just did.

How hooks work

To understand hooks, first look at the normal flow without them. Suppose you ask Claude Code to “open the config file and add a setting.” Without hooks, the flow mentioned below is initiated.

1. User prompt: Your request goes to Claude.

2. Claude chooses a tool: Claude might use the Read tool to open the file, then the Edit tool to modify it.

3. Tool execution: Claude Code executes those tool actions (reading or editing the file) and returns the results to Claude.

4. Claude responds: Claude continues the conversation and uses the tool results to formulate their answer.

Hooks let us inject our own steps into this flow. Your hooks are ordinary shell commands or scripts that can do anything you allow in your environment, giving you fine-grained control over Claude’s actions.

Types of Hooks: PreToolUse vs. PostToolUse

Claude Code supports several hook events, but the primary ones are PreToolUse and PostToolUse.

• PreToolUse hooks: Execute before a tool runs. They can prevent the tool from running if needed. For example, a PreToolUse hook can check whether Claude is about to read a sensitive file and block that action. Because they run beforehand, PreToolUse hooks are ideal for guarding or gating actions. To block a tool, the hook signals an error, and Claude typically does not proceed with the tool call.

• PostToolUse hooks: Execute after a tool has run successfully. They cannot stop the tool (because it has already run), but they can perform follow-up tasks. For example, a PostToolUse hook might automatically format a file that Claude just edited or run tests after new code is written. PostToolUse hooks are great for cleanup, enforcement, or as an extension of Claude’s output.

There are other types of hooks ...