How Claude Code Hooks Save Me HOURS Daily

These notes are based on the YouTube video by Better Stack

Introduction to Claude Code Hooks

Claude Code hooks are a powerful feature that allows users to run custom scripts automatically for specific events. There are six types of hooks:

PreToolUse
PostToolUse
Notification
Stop
SubagentStop
UserPromptSubmit

Creating Custom Hooks

To create a custom hook, use the hooks slash command. This will display a warning, as hooks are commands that run without confirmation. To create a hook, follow these steps:

Choose a hook type (e.g., PreToolUse)
Specify the script to execute for the chosen hook event
Ensure the script is executable in the environment where Claude Code runs
Save the hook configuration according to the Claude Code interface or platform guidelines

Hook Input and Scripting

Hooks receive structured data (often JSON) as input, which can be used to create more detailed logs or trigger specific actions. For example, a script can be written in any language that can process the input and produce the desired output to take the hook input and create a JSON log:

{
  "tool": "bash",
  "command": "ls -l"
}

This log can be used for auditing or improving tool usage. Note that while scripts can be written in any language, they must be executable in the environment where Claude Code runs, which may require additional setup for non-shell scripts.

Exit Codes and Error Handling

In a script, triggering an exit code of 2 will block the tool call or prompt and show an error to Claude or the user, depending on the hook type. This can be used to block specific commands. For example, a hook can be created to block Claude from using NPM:

# use bun hook
if [ "$TOOL" == "npm" ]; then
  echo "Error: NPM is not allowed."
  exit 2
fi

This script blocks NPM and outputs an error; to automatically reroute the command to an alternative like bun, additional scripting logic would be required.

Advanced Use Cases

Hooks can be used for a variety of purposes, such as:

Showing linting errors
Blocking access to sensitive files
Playing audio notifications
Sending notifications to a phone

Summary

Claude Code hooks provide a high level of control and customization, allowing users to automate specific tasks and improve their workflow. By creating custom hooks and using exit codes, users can tailor their experience to their specific needs. With the ability to write scripts in any executable language and trigger alternative actions, the possibilities are extensive. Understanding the precise behavior of hooks, including how they are created, saved, and interact with the model, is crucial for maximizing their potential.

# How Claude Code Hooks Save Me HOURS Daily