Consult Google Gemini CLI for second opinions on architecture, debugging, and security audits. Use Gemini's 1M+ context window for comprehensive code analysis...
Leverage Gemini's 1M+ context window as your AI pair programmer within Claude Code workflows.
This skill teaches Claude Code how to use the official Google Gemini CLI (gemini command) to get second opinions, architectural advice, debugging help, and comprehensive code reviews. Based on production testing with the official CLI tool.
Prerequisites:
npm install -g @google/gemini-cli)gemini once to authenticate)Basic Usage Patterns:
# Quick question (non-interactive with -p flag)
gemini -p "Should I use D1 or KV for session storage?"
# Code review with file context (using --all-files)
gemini --all-files -p "Review this auth implementation for security issues"
# Architecture advice using Pro model
gemini -m gemini-2.5-pro -p "Best way to handle WebSockets in Cloudflare Workers?"
# Pipe file content for review
cat src/auth.ts | gemini -p "Review this authentication code for security vulnerabilities"
# Interactive mode for follow-up questions
gemini -i "Help me debug this authentication error"
Claude Code should automatically invoke Gemini in these situations:
Major Architectural Decisions
gemini -m gemini-2.5-pro -p "[architectural question]"Security-Sensitive Code Changes
cat [security-file] | gemini -m gemini-2.5-pro -p "Security audit this code"Large Refactors
gemini --all-files -m gemini-2.5-pro -p "Review this refactoring plan"Stuck Debugging (2+ Failed Attempts)
gemini -p "Help debug: [error message]" < error.logContext Window Pressure (70%+ Full)
cat large-file.ts | gemini -p "Analyze this code structure"Unfamiliar Technology
gemini -p "Best practices for [new technology]"Code Reviews
git diff | gemini -p "Review these changes"npm install -g @google/gemini-cli
gemini
Follow the authentication prompts to link your Google account.
gemini --version
Should show version 0.13.0 or higher.
gemini -p "What is 2+2?"
-p flag)Best for Claude Code integration:
# Direct question
gemini -p "Your question here"
# With model selection
gemini -m gemini-2.5-flash -p "Quick debugging question"
gemini -m gemini-2.5-pro -p "Complex architectural decision"
# With file context via pipe
cat src/auth.ts | gemini -p "Review this code"
# With all files in current directory
gemini --all-files -p "Analyze project structure"
# With stdin input
echo "Error: Cannot connect to database" | gemini -p "Help debug this error"
-i flag)For follow-up conversations:
# Start interactive session with initial prompt
gemini -i "Let's discuss the architecture"
# Interactive with model selection
gemini -m gemini-2.5-pro -i "Help me design a database schema"
-y flag)Auto-accepts all actions (use with caution):
# Dangerous: Auto-executes suggested commands
gemini -y -p "Fix all linting errors"
⚠️ Warning: YOLO mode can execute commands without confirmation. Only use in trusted environments.
Characteristics:
Use For:
Example:
gemini -m gemini-2.5-flash -p "Review this function for performance issues"
Characteristics:
Use For:
Example:
gemini -m gemini-2.5-pro -p "Security audit this authentication system"
Characteristics:
Use For:
Example:
gemini -m gemini-3-pro-preview -p "Deep architectural analysis of this distributed system"
cat architecture-diagram.png | gemini -m gemini-3-pro-preview -p "Analyze this system design"
⚠️ Preview Status: Model is in preview. For production-critical decisions, consider using gemini-2.5-pro (stable) until Gemini 3 reaches general availability.
Quick question? → Flash
Security/architecture? → 3-Pro-Preview (cutting-edge) or 2.5-Pro (stable)
Debugging? → Flash (try Pro if stuck)
Code review? → Flash
Refactoring 5+ files? → 3-Pro-Preview or 2.5-Pro
Multimodal analysis? → 3-Pro-Preview
Trigger: User asks about technology choice Claude Action: Automatically consult Gemini for second opinion
# Claude runs:
gemini -m gemini-2.5-pro -p "Compare D1 vs KV for session storage in Cloudflare Workers. Consider: read/write patterns, cost, performance, complexity."
# Then synthesizes both perspectives
Trigger: Working on auth/payment/sensitive code Claude Action: Request Gemini security audit
# Claude runs:
cat src/auth/verify-token.ts | gemini -m gemini-2.5-pro -p "Security audit this authentication code. Check for: token validation, timing attacks, injection vulnerabilities, error handling."
Trigger: Error persists after 2 attempts Claude Action: Get Gemini's perspective
# Claude runs:
echo "[error message and stack trace]" | gemini -p "Help debug this error. What's the likely root cause?"
Trigger: Major changes ready to commit Claude Action: Request comprehensive review
# Claude runs:
git diff HEAD | gemini --all-files -p "Review these changes for: correctness, edge cases, performance, security, best practices."
✅ GOOD: Context-Rich, Specific
gemini -m gemini-2.5-pro -p "I'm building a Cloudflare Worker with user authentication. Should I use D1 or KV for storing session data? Consider: 1) Session reads on every request, 2) TTL-based expiration, 3) Cost under 10M requests/month, 4) Deployment complexity."
❌ BAD: Vague, No Context
gemini -p "D1 or KV?"
[Context: What you're building]
[Question]
[Considerations: Key factors (numbered)]
gemini -m gemini-2.5-pro -p "
Context: Building a real-time collaborative editing app on Cloudflare Workers.
Question: Should I use Durable Objects or Workflows for managing document state?
Considerations:
1. Need to handle WebSocket connections (100+ simultaneous users per document)
2. Document state must be consistent across all clients
3. Need to persist changes every 5 seconds
4. Budget: <\$100/month at 1000 documents
5. Simple deployment preferred
"
# Compare two technologies
gemini -m gemini-2.5-pro -p "Compare Drizzle ORM vs raw SQL for Cloudflare D1. Consider: type safety, performance, query complexity, bundle size."
# Audit authentication code
cat src/middleware/auth.ts | gemini -m gemini-2.5-pro -p "
Security audit this authentication middleware. Check for:
1. Token validation vulnerabilities
2. Timing attack risks
3. Error handling leaks
4. CSRF protection
5. Rate limiting
"
# Analyze error logs
tail -100 error.log | gemini -p "
These errors started appearing after deploying auth changes. What's the likely root cause?
Context:
- Added JWT validation middleware
- Using @cloudflare/workers-jwt
- Errors only on /api/* routes
"
# Review pull request changes
git diff main...feature-branch | gemini --all-files -p "
Review this pull request. Focus on:
1. Breaking changes
2. Edge cases not handled
3. Performance implications
4. Security concerns
"
# Plan large refactor
gemini --all-files -m gemini-2.5-pro -p "
I want to refactor this Express app to Cloudflare Workers with Hono. Analyze the codebase and suggest:
1. Migration order (which routes first)
2. Potential blockers (middleware that won't work)
3. Testing strategy
4. Deployment plan
"
# Analyze performance
cat src/api/heavy-endpoint.ts | gemini -p "
This endpoint is slow (500ms+ response time). Identify performance bottlenecks and suggest optimizations.
Context:
- Cloudflare Worker
- Fetches data from 3 external APIs
- Processes 1000+ items
"
Scenario: User asks architectural question
User: "Should I use D1 or KV for storing user sessions?"
Claude (internal): This is an architectural decision. Consult Gemini for second opinion.
[Runs: gemini -m gemini-2.5-pro -p "Compare D1 vs KV for user session storage in Cloudflare Workers..."]
Claude (to user): "I've consulted Gemini for a second opinion. Here's what we both think:
My perspective: [Claude's analysis]
Gemini's perspective: [Gemini's analysis]
Key differences: [synthesis]
Recommendation: [combined recommendation]"
User: "Ready to commit these auth changes"
Claude (internal): Security-sensitive code. Request Gemini audit.
[Runs: cat src/auth/*.ts | gemini -m gemini-2.5-pro -p "Security audit..."]
Claude (to user): "I've reviewed the code and consulted Gemini for security concerns:
Gemini identified: [security issues]
Additional checks I recommend: [Claude's additions]
Safe to commit after addressing: [list]"
User: "Still getting this error after trying your suggestions: [error]"
Claude (internal): Two failed attempts. Consult Gemini for fresh perspective.
[Runs: echo "[error details]" | gemini -p "Help debug..."]
Claude (to user): "Let me get a second opinion from Gemini...
Gemini suggests: [Gemini's diagnosis]
This makes sense because: [Claude's analysis]
Let's try: [combined solution]"
Error: Error: Not authenticated
Solution:
gemini
# Follow authentication prompts
Error: Error: Model not found: gemini-2.5-flash-lite
Cause: Model deprecated or renamed
Solution:
# Use stable models
gemini -m gemini-2.5-flash -p "Your question"
gemini -m gemini-2.5-pro -p "Your question"
Error: Error: Rate limit exceeded
Solution: Wait 1-5 minutes, then retry
Prevention: Space out requests
Error: File too large for context
Solution: Use --all-files carefully or pipe specific sections
# Instead of:
gemini --all-files -p "Review everything"
# Do:
cat src/specific-file.ts | gemini -p "Review this file"
Cause: Interactive mode when expecting non-interactive
Solution: Always use -p flag for non-interactive commands
# ✅ Correct
gemini -p "Question"
# ❌ Wrong (will hang waiting for input)
gemini "Question"
-p for Automation# ✅ Good for scripts
gemini -p "Question"
# ❌ Bad for scripts (interactive)
gemini
# Architecture/security → Pro
gemini -m gemini-2.5-pro -p "[critical question]"
# Debugging/review → Flash
gemini -m gemini-2.5-flash -p "[general question]"
# ✅ Good
gemini -p "Context: Building Cloudflare Worker. Question: Best auth pattern? Considerations: 1) Stateless, 2) JWT, 3) <100ms overhead"
# ❌ Bad
gemini -p "Best auth?"
# ✅ Good
cat src/auth.ts | gemini -p "Review for security"
# ❌ Inefficient
gemini -p "Review src/auth.ts" # Gemini has to read file separately
# Add error handling
if output=$(gemini -p "Question" 2>&1); then
echo "Gemini says: $output"
else
echo "Gemini consultation failed, proceeding with Claude's recommendation"
fi
❌ BAD: Just paste Gemini's response
User: "Should I use D1?"
Claude: [runs gemini] "Gemini says: [paste]"
✅ GOOD: Synthesize both perspectives
User: "Should I use D1?"
Claude: [runs gemini]
"I've consulted Gemini for a second opinion:
My analysis: [Claude's perspective]
Gemini's analysis: [Gemini's perspective]
Key differences: [synthesis]
Recommendation: [unified answer]"
2.1.0 (2025-11-19):
gemini-3-pro-preview)2.0.0 (2025-11-13):
gemini CLI v0.13.0+1.0.0 (2025-11-08):
MIT - See LICENSE
