Codex Explain Skill

Trigger

• Keywords: explain code, what does this do, how does this work, code walkthrough

When NOT to Use

• Code review (use codex-code-review)
• Bug investigation (use bug-fix or issue-analyze)
• Architecture overview (use code-explore)

Workflow

Read target → [Collect context] → Codex explain → Output explanation

Step 1: Read Target File

Read file content. If --lines specified, extract only that range.

Step 2: Codex Explanation

Use mcp__codex__codex with explanation prompt. See @references/codex-prompt-explain.md.

Config: sandbox: 'read-only', approval-policy: 'never'

Depth Levels

Level	Description
brief	One-sentence summary
normal	Functional overview + execution flow + key concepts (default)
deep	+ Design patterns + complexity + issues + dependencies

Output

## Code Explanation: <target>
- **Depth**: brief / normal / deep
- **Summary**: <functional overview>
- **Execution flow**: <key paths>
- **Key concepts**: <patterns, abstractions>

Verification

• Codex independently researched project context (imports, callers)
• Explanation matches requested depth level
• Key concepts are identified and explained

References

• Explanation prompt: references/codex-prompt-explain.md

Examples

Input: /codex-explain src/service/order/order.service.ts
Action: Read file → Codex explain (normal) → Functional summary + detailed explanation

Input: /codex-explain src/service/xxx.ts --depth deep
Action: Read file → Codex explain (deep) → Patterns + complexity + issues

Input: /codex-explain src/xxx.ts --lines 50-100
Action: Read lines 50-100 → Codex explain → Focused explanation