plan-review

name	plan-review
description	Get Codex's review of Claude's implementation plans via the Codex MCP server. Trigger when user wants a second opinion on a plan ("have Codex review this plan", "get second opinion from Codex", "critique this plan with Codex"), or after Claude creates a plan file that needs validation before implementation.

Plan Review via Codex

Use Codex to critique implementation plans for gaps, risks, and better alternatives. Codex consults; Claude writes.

Transport

Always use the MCP tool. The plugin runs codex mcp-server on stdio via .mcp.json. Tool name: mcp__plugin_codex_cli__codex. If the example below errors with an unknown-tool error, run /mcp and substitute the actual prefix (e.g., mcp__codex_cli__codex).

Model

Omit model to use the default (gpt-5.5). Plan review benefits from flagship reasoning — don't downgrade to gpt-5.4-mini here. Only set model if the user explicitly names one. See ../references/patterns.md.

Flow

Codex reads files from the project root. For plans living outside the repo (e.g., ~/.claude/plans/...), read them with Claude's Read tool first and embed the content in the prompt. Codex doesn't expand shell substitutions and can't see paths outside its cwd.

mcp__plugin_codex_cli__codex({
  "prompt": "Review this implementation plan:\n\n---\n[PLAN CONTENT HERE]\n---\n\nConsider:\n1. Gaps or missing steps?\n2. Risks not addressed?\n3. Is the approach optimal? What alternatives should we consider?",
  "sandbox": "read-only"
})

If the plan lives inside the repo, you can just reference the path:

mcp__plugin_codex_cli__codex({
  "prompt": "Review the implementation plan at docs/plans/auth-rewrite.md. Flag gaps, risks, and better alternatives.",
  "sandbox": "read-only"
})

With source context

Let Codex cross-check the plan against the actual code:

mcp__plugin_codex_cli__codex({
  "prompt": "Review this plan:\n\n[PLAN CONTENT]\n\nRead these source files for context before critiquing:\n- src/auth/login.ts\n- src/middleware/session.ts\n\nEvaluate whether the plan accounts for the real code structure.",
  "sandbox": "read-only"
})

Focused reviews

Risk assessment:

mcp__plugin_codex_cli__codex({
  "prompt": "Risk review of this plan:\n\n[PLAN CONTENT]\n\nEvaluate:\n- Breaking changes\n- Data loss potential\n- Rollback complexity\n- Dependencies that could fail",
  "sandbox": "read-only"
})

Completeness check:

mcp__plugin_codex_cli__codex({
  "prompt": "Completeness review of this plan:\n\n[PLAN CONTENT]\n\nEvaluate:\n- Edge cases covered?\n- Testing addressed?\n- Missing steps?",
  "sandbox": "read-only"
})

Iterative workflow (prefer codex-reply)

When you're still iterating on the same plan, continue the existing thread rather than starting a new codex call. Codex keeps the plan and its prior critique in context; starting fresh discards that reasoning and forces re-reading.

Typical loop: initial critique → Claude revises the plan → codex-reply with the revised sections asking "does this address your concern?" → Codex confirms or pushes back → repeat.

Cap at 3–4 rounds total. Plan review should converge fast; if you're still going at round 5, stop and surface the open questions to the user rather than letting the dialog spiral.

threadId is an MCP argument — pass it as the threadId field of codex-reply, not in the prompt text. See ../references/mcp-schema.md for wrong-vs-right examples.

Example — three rounds on the same plan:

# Round 1 — initial critique
mcp__plugin_codex_cli__codex({
  "prompt": "Review this plan:\n\n[PLAN CONTENT]\n\nFlag gaps, risks, and better alternatives.",
  "sandbox": "read-only"
})
# → threadId: "019da14b-..."  /  flags: "No rollback strategy for the schema migration in step 3."

# Round 2 — Claude revises and resubmits only the changed section
mcp__plugin_codex_cli__codex-reply({
  "threadId": "019da14b-...",
  "prompt": "Revised step 3 to use an expand-contract migration with a reversible intermediate state:\n\n[REVISED SECTION]\n\nDoes this address the rollback concern?"
})

# Round 3 — triage remaining risks
mcp__plugin_codex_cli__codex-reply({
  "threadId": "019da14b-...",
  "prompt": "Of the risks you flagged, which would actually block merge vs. which can be mitigated post-launch?"
})

Start a fresh thread when: reviewing a different plan, the threadId is no longer in context, or the plan has been rewritten so substantially that re-priming is cleaner than patching. See ../references/patterns.md.

Recommended pattern

1. If the plan is outside the workspace, use Claude's Read to fetch it.
2. Embed the plan content in the Codex prompt.
3. List any in-repo source files Codex should read for context.
4. Use codex-reply to drill in rather than starting new threads.

Performance

• Plan-only review: ~5–30 s
• Plan + source cross-check: ~1–2 min

Safety

• Always sandbox: "read-only".
• Never use workspace-write, danger-full-access, or --dangerously-bypass-approvals-and-sandbox.

Fallback (rare)

If the MCP server is unavailable, see ../references/commands.md for the Bash codex exec form. Requires dangerouslyDisableSandbox: true. Don't pipe with $(cat plan.md) — Codex doesn't expand shell substitutions; either embed the content or pass a repo-relative path.