| name | codex-explain |
| description | Explain complex code via Codex MCP. Use when: understanding complex logic, tracing data flow, onboarding to unfamiliar code. Not for: code review (use codex-code-review), exploration (use code-explore). Output: structured explanation at chosen depth. |
| allowed-tools | mcp__codex__codex, mcp__codex__codex-reply, Read, Grep, Glob |
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
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
