Getting Started with 2ndOpinion in 5 Minutes

2ndOpinion gives you AI-to-AI code review — send your diffs to Claude, Codex, and Gemini, and get structured risk analysis, alternative approaches, and clear accept/review/reject recommendations. Here is how to set it up in under five minutes, whether you prefer MCP, the command line, or a raw API.

Option 1: MCP Server (Recommended for Claude Code and Cursor)

If you use Claude Code, Cursor, Windsurf, or any MCP-compatible editor, this is the fastest path. The MCP server gives you 10 review tools directly inside your editor.

Step 1: Get an API Key

Sign up at get2ndopinion.dev/signup and create an API key from your dashboard. Your key will look like sk_2op_....

Step 2: Install the MCP Server

Add this to your MCP configuration:

{
  "mcpServers": {
    "2ndopinion": {
      "command": "npx",
      "args": ["-y", "@2ndopinion/mcp@latest"],
      "env": {
        "SECONDOPINION_API_KEY": "sk_2op_your_key_here"
      }
    }
  }
}

For Claude Code, this goes in ~/.claude/claude_desktop_config.json. For Cursor, add it in Settings > MCP.

Step 3: Use It

Once configured, you have access to these tools directly in your editor:

• second_opinion — Get a single-model code review of your current diff
• consensus_review — Run all three models and get a consensus analysis
• bug_hunt — Search for bugs with three models simultaneously
• security_audit — OWASP-aligned security analysis
• generate_tests — Generate runnable tests for your changes
• ai_debate — Watch models debate the best approach to a problem
• ask_other_model — Ask any model a freeform question
• explain_changes — Get plain-English explanations for technical or non-technical audiences
• review_pr — Review a GitHub pull request by URL
• get_usage — Check your remaining credits

Just ask your AI assistant something like "run a consensus review on my staged changes" and it will call the right tool automatically.

Option 2: CLI

The CLI works in any terminal and integrates with git. It auto-detects your staged or unstaged changes.

Step 1: Install

npm install -g 2ndopinion

Step 2: Authenticate

2ndopinion login

This opens a browser-based auth flow. Alternatively, log in with an API key:

2ndopinion login --api-key sk_2op_your_key_here

Step 3: Review Your Code

From inside any git repository:

# Review your current unstaged changes
2ndopinion review

# Review staged changes
2ndopinion review --staged

# Review with a specific model
2ndopinion review --model claude

# Ask a freeform question
2ndopinion ask "Is this rate limiting implementation correct?"

# Get a consensus review (uses 3 credits)
2ndopinion consensus

The CLI outputs structured results directly in your terminal — risk levels, affected files, explanations, and a final recommendation.

Useful CLI Options

# Set your preferred default model
2ndopinion config set defaultLlm codex

# Check your usage and remaining credits
2ndopinion status

# Review a specific file's diff
git diff src/auth.ts | 2ndopinion review --stdin

Option 3: HTTP API

If you want to integrate 2ndOpinion into CI/CD pipelines, custom tools, or scripts, you can call the API directly.

Authentication

Include your API key in the X-2ndOpinion-Key header:

curl -X POST https://get2ndopinion.dev/api/gateway/opinion \
  -H "Content-Type: application/json" \
  -H "X-2ndOpinion-Key: sk_2op_your_key_here" \
  -d '{
    "diff": "your git diff here",
    "model": "claude"
  }'

Key Endpoints

Endpoint	What It Does	Credits
POST /api/gateway/opinion	Single-model review	1
POST /api/gateway/consensus	Three-model consensus	3
POST /api/gateway/bug-hunt	Three-model bug hunt	3
POST /api/gateway/security-audit	OWASP security audit	1-3
POST /api/gateway/ask	Freeform question	1
POST /api/gateway/generate-tests	Generate tests	1
GET /api/gateway/status	Account and usage info	0

Example: Consensus Review

curl -X POST https://get2ndopinion.dev/api/gateway/consensus \
  -H "Content-Type: application/json" \
  -H "X-2ndOpinion-Key: sk_2op_your_key_here" \
  -d '{
    "diff": "'"$(git diff)"'"
  }'

The response includes individual analyses from each model, clustered agreements and disagreements, and a final consensus recommendation.

Option 4: JavaScript and Python SDKs

For programmatic access in your applications:

JavaScript

npm install @2ndopinion/sdk

import { SecondOpinion } from '@2ndopinion/sdk';

const client = new SecondOpinion({ apiKey: 'sk_2op_...' });

const result = await client.review({
  diff: gitDiff,
  model: 'claude',
});

console.log(result.recommendation); // 'approve' | 'review' | 'reject'

Python

pip install secondopinion

from secondopinion import SecondOpinion

client = SecondOpinion(api_key="sk_2op_...")

result = client.review(diff=git_diff, model="claude")
print(result.recommendation)

Zero-Install: The Playground

If you want to try 2ndOpinion without installing anything, head to the playground. Paste a diff or code snippet, pick a tool, and see the results immediately. No API key required for the playground.

What You Get on the Free Tier

Every account starts with 5 credits per month. That is enough for:

• 5 single-model reviews, or
• 1 consensus review + 2 single-model reviews, or
• 1 bug hunt + 2 questions

If you need more, the Pro plan ($10/month) gives you 100 credits, Power ($25/month) gives you 500, and Agent ($49/month) gives you 1,000. You can also buy credit packs as one-time purchases if you do not want a subscription.

Next Steps

Once you are up and running, explore the full set of tools in the documentation. The skills marketplace has community-created review prompts for specific frameworks and patterns — things like React performance audits, SQL migration reviews, and API design checks.

If you build a custom integration, we would love to hear about it. Reach out on X/Twitter.