Claude Code + Codex Dual Review

.mcp.json

{
  "mcpServers": {
    "codex": {
      "type": "stdio",
      "command": "codex",
      "args": ["mcp-server"]
    }
  }
}

dual-review.md

Dual Review: Claude + Codex

Review an implementation plan with Codex before presenting it to the user.

You MUST follow this protocol exactly. Do not skip steps.

Step 1: Draft the Plan

Based on the user's task: $ARGUMENTS

Explore the codebase thoroughly, then draft a detailed implementation plan. Include:

• Files to create/modify with specific changes
• Architecture decisions and rationale
• Potential risks or trade-offs

Step 2: Send to Codex for Review

Send the plan to Codex using mcp__codex__codex with this prompt:

You are a senior engineer reviewing an implementation plan. Your job is to find problems, gaps, and suggest improvements.

Review this plan and respond with ONLY a JSON object (no markdown, no code fences):

{
  "verdict": "APPROVED" or "NEEDS_REVISION",
  "issues": [
    {
      "severity": "critical" | "major" | "minor",
      "description": "What's wrong",
      "recommendation": "How to fix it"
    }
  ],
  "suggestions": ["Optional improvement ideas that aren't blocking"]
}

Rules:
- "critical" = will cause bugs, security issues, or data loss. Must be fixed.
- "major" = significant design flaw or missing requirement. Should be fixed.
- "minor" = style, naming, or small improvements. Nice to have.
- Use APPROVED only when there are zero critical or major issues.
- Be specific. Reference file names, function names, line numbers when possible.

THE PLAN:
<insert your drafted plan here>

Save the threadId from the response for follow-up rounds.

Step 3: Process the Review

Parse the JSON response from Codex.

If APPROVED: Go to Step 5.

If NEEDS_REVISION: For each issue, do one of:

• Accept: Modify the plan to address the issue. State what you changed.
• Reject: Explain why the issue doesn't apply or why your approach is better.

Then send the updated plan back to Codex using mcp__codex__codex-reply with the same threadId:

I've addressed your review. Here are my responses to each issue:

<for each issue, state: ACCEPTED (with change description) or REJECTED (with reasoning)>

UPDATED PLAN:
<insert updated plan>

Please review again. Same JSON format.

Step 4: Iterate (Max 3 Rounds)

Repeat Step 3 up to 3 total rounds. Track the round number.

If after 3 rounds there is still no APPROVED verdict:

• Present the plan with remaining disagreements clearly marked
• Show Codex's position vs your position for each unresolved issue
• Let the user decide

Step 5: Present Final Result

Present the final plan to the user with two sections:

Implementation Plan

The agreed-upon plan.

Review History

A summary of the review process:

• Number of rounds
• Issues raised and how they were resolved (accepted/rejected)
• Any remaining disagreements (if max rounds reached)
• Codex's final verdict

Format the review history as a collapsible details block:

<details>
<summary>Codex Review: {verdict} after {N} round(s) — {X} issues raised, {Y} accepted, {Z} rejected</summary>
... full review back-and-forth ...
</details>

nit pick

"verdict": "APPROVED" or "NEEDS_REVISION", → "verdict": "APPROVED" | "NEEDS_REVISION",

Can benefit from the frontmatter:

---
name: dual-review
description: Draft an implementation plan and have Codex review it before presenting to the user. Use for complex tasks, architectural decisions, or multi-file changes that benefit from a second opinion.
---