second-opinions

Original：🇺🇸 English

Translated

Use when wanting independent review from external models before merging, committing, or finalizing architecture or plan decisions, or when the user asks for a second opinion, codex review, or gemini review

1installs

Sourcevinta/hal-9000

Added on2026-02-23

NPX Install

npx skill4agent add vinta/hal-9000 second-opinions

SKILL.md Content

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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:

bash

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]