Claude Code hooks: intercept every tool call before it runs

Claude Code hooks: intercept every tool call before it runs The Claude Code source leak revealed something most developers haven't discovered yet: a full hooks system that lets you intercept, log, or block any tool call Claude makes — before it executes. This isn't documented anywhere officially. Here's how it works. What are Claude Code hooks? Hooks are shell commands that run at specific points in Claude Code's execution cycle: PreToolUse — runs before Claude calls any tool (Bash, Read, Write, etc.) PostToolUse — runs after a tool completes Notification — runs when Claude sends you a notification Stop — runs when a session ends You define them in your .claude/settings.json. The config format { "hooks": { "PreToolUse": [ { "matcher": "Bash", "hooks": [ { "type": "command", "command": "echo '[HOOK] Claude about to run Bash' >> /tmp/claude-audit.log" } ] } ], "PostToolUse": [ { "matcher": "Write", "hooks": [ { "type": "command", "command": "echo '[HOOK] Claude wrote a file' >&g