Hook Developer Complete reference for developing Claude Code hooks. Use this to write hooks with correct input/output schemas. When to Use - Creating a new hook - Debugging hook input/output format - Understanding what fields are available - Setting up hook registration in settings.json - Learning what hooks can block vs inject context Quick Reference | Hook | Fires When | Can Block? | Primary Use | |------|-----------|------------|-------------| | PreToolUse | Before tool executes | YES | Block/modify tool calls | | PostToolUse | After tool completes | Partial | React to tool results | | Use…