Hook Development for Claude Code FAQs

Question 1

What are prompt-based hooks in Claude Code?

Accepted Answer

Prompt-based hooks use natural language instructions to let the LLM evaluate whether a specific action, such as a tool call, should be approved, denied, or modified based on the current context.

Question 2

What is the difference between PreToolUse and PostToolUse?

Accepted Answer

PreToolUse executes before a tool runs to allow for validation or modification of inputs, while PostToolUse executes after completion to analyze results and provide feedback.

Question 3

How do matchers work in hook configuration?

Accepted Answer

Matchers use exact strings, regex, or wildcards to define which tools or events a hook should apply to, such as matching all 'Write' operations or all MCP-prefixed tools.

Question 4

How do I persist environment variables across a Claude session?

Accepted Answer

You can use a SessionStart hook to append export commands to the $CLAUDE_ENV_FILE, which ensures those variables are available to Claude for the duration of the session.

Question 5

Can I use bash scripts to validate Claude's actions?

Accepted Answer

Yes, command hooks allow you to execute deterministic bash scripts for tasks like file system checks, running linters, or integrating with external CLI tools.

Hook Development for Claude Code

Key Features

Use Cases

Hook Development for Claude Code

Key Features

Use Cases