James' Growth Diary

Apr 29, 2026 · Information Security

Claude Code’s Five‑Layer Permission System: How It Stops Unauthorized Tool Calls

The article dissects Claude Code’s built‑in five‑layer permission architecture, explaining why a single check is insufficient, how each layer (Hooks, Deny Rules, Permission Mode, Allow Rules, canUseTool) works, the engineering trade‑offs, performance concerns, and practical recommendations for secure AI agent deployments.