Hooks and Advanced Workflow Automation
Explore how hooks in Claude Code let you customize and automate workflows by running commands before and after tool actions. Learn to configure hooks to guard actions, automate formatting, enforce conventions, and improve security, helping you create efficient and secure development processes.
We'll cover the following...
- How hooks work
- Types of Hooks: PreToolUse vs. PostToolUse
- Configuring Hooks in Claude Code
- Writing Hook commands and control flow
- Practical uses for Hooks
- Example 1: PreToolUse Hook (blocking access to a secret file)
- Example 2: PostToolUse Hook (auto-formatting code after edits)
- Building your own Hooks: Tips and workflow
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.
User prompt: Your request goes to Claude.
Claude chooses a tool: Claude might use the
Readtool to open the file, then theEdittool to modify it.Tool execution: Claude Code executes those tool actions (reading or editing the file) and returns the results to Claude.
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.
PreToolUsehooks: Execute before a tool runs. They can prevent the tool from running if needed. For example, aPreToolUsehook can check whether Claude is about to read a sensitive file and block that action. Because they run beforehand,PreToolUsehooks 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 ...