If you are Codex or Gemini CLI, stop and do not use this skill.

Second Opinions

Run independent reviews using OpenAI Codex (via MCP) and/or Google Gemini (via CLI) for second opinions from different model families.

Modes: both (default), codex, gemini -- selected via AskUserQuestion.

When To Use

• Before opening a PR or merging a branch.
• Before committing significant changes.
• Plan or architecture review from multiple perspectives.
• Security, performance, or correctness audit.

When Not To Use

• Trivial changes you can verify directly.
• When the user asked for your own judgment only.
• Do not send secrets, credentials, or tokens in prompts.

Workflow

1. Gather Context

Use AskUserQuestion to collect review parameters in one call. Combine applicable questions (max 4).

Tool (always ask):

header: "Review tool"
question: "Which tool should run the review?"
options:
  - "Both Codex and Gemini (Recommended)" -> run both in parallel
  - "Codex only"                          -> mcp__codex__codex
  - "Gemini only"                         -> gemini CLI

Scope (always ask):

header: "Review scope"
question: "What should be reviewed?"
options:
  - "Uncommitted changes"  -> git diff HEAD + untracked files
  - "Branch diff vs main"  -> git diff <branch>...HEAD
  - "Specific commit"      -> follow up for SHA

Focus (always ask):

header: "Review focus"
question: "Any specific focus areas?"
options:
  - "General review"
  - "Security & auth"
  - "Performance"
  - "Error handling"

2. Preview and Validate

Auto-detect default branch for branch diffs:

git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@' || echo main

Show diff stats for the selected scope. If empty, stop and tell the user. If >2000 lines changed, warn and ask whether to proceed or narrow scope.

3. Dispatch Reviews

Project context: If a CLAUDE.md exists in the repo root, always include it in the review prompt so reviewers check against project conventions.

Run the selected tool(s). When running both, issue mcp__codex__codex and Bash(gemini ...) calls in a single message for parallel execution. Both are read-only operations with no shared state.

See references/codex.md for Codex MCP patterns.
See references/gemini.md for Gemini CLI patterns.

Do not pre-check tool availability. If a tool fails, report the install instructions from the error handling table and run only the available tool.

4. Present Results

When running both, present with clear headers:

## Codex Review
<codex findings>

## Gemini Review
<gemini findings>

## Summary
Where the two reviews agree and differ.
Prioritized action items.

When running a single tool, present its findings directly with your assessment of which findings are valid vs uncertain.

Error Handling

Error	Action
mcp__codex__codex unavailable	Run Gemini only,
gemini: command not found	Run Codex only.
Both unavailable	Stop and inform the user
Gemini extension missing	Install: gemini extensions install <github-url> (see gemini reference)
Empty diff	Stop: no changes to review
Timeout	Suggest narrowing the scope
One tool fails	Present the other's results, note the failure

Examples

Both tools (default):

User: /second-opinions
Agent: [asks 3 questions: tool, scope, focus]
User: picks "Both", "Branch diff", "Security"
Agent: [detects default branch = main, shows diff --stat]
Agent: [auto-includes CLAUDE.md, dispatches mcp__codex__codex + gemini in parallel]
Agent: [presents both reviews, highlights agreements/differences]

Single tool:

User: /second-opinions
Agent: [asks 3 questions: tool, scope, focus]
User: picks "Codex only", "Uncommitted", "General"
Agent: [shows diff --stat]
Agent: [calls mcp__codex__codex with review prompt]
Agent: [presents findings with assessment]

Large diff warning:

User: /second-opinions
Agent: [asks questions] -> user picks "Both", "Uncommitted", "General"
Agent: [shows diff --stat: 45 files, +3200 -890]
Agent: "Large diff (3200+ lines). Proceed, or narrow the scope?"
User: "proceed"
Agent: [runs both reviews]