Gemini CLI Integration Skill

This skill enables Claude Code to effectively orchestrate Gemini CLI (v0.27.0+) for code generation, review, analysis, and specialized tasks. The default model is Auto routing (automatically selects between Flash and Pro based on task complexity).

When to Use This Skill

Ideal Use Cases

1. Second Opinion / Cross-Validation

   • Code review after writing code (different AI perspective)
   • Security audit with alternative analysis
   • Finding bugs Claude might have missed

2. Google Search Grounding

   • Questions requiring current internet information
   • Latest library versions, API changes, documentation updates
   • Current events or recent releases

3. Codebase Architecture Analysis

   • Use Gemini's codebase_investigator tool
   • Understanding unfamiliar codebases
   • Mapping cross-file dependencies

4. Parallel Processing

   • Offload tasks while continuing other work
   • Run multiple code generations simultaneously
   • Background documentation generation

5. Specialized Generation

   • Test suite generation
   • JSDoc/documentation generation
   • Code translation between languages

When NOT to Use

• Simple, quick tasks (overhead not worth it)
• Tasks requiring immediate response (rate limits cause delays)
• When context is already loaded and understood
• Interactive refinement requiring conversation

Core Instructions

1. Verify Installation

command -v gemini || which gemini

2. Basic Command Pattern

gemini "[prompt]" --approval-mode yolo -o text 2>&1

Key flags:

• --approval-mode yolo: Auto-approve all tool calls (replaces deprecated --yolo)
• -o text: Human-readable output
• -o json: Structured output with stats
• -m gemini-2.5-flash: Use faster model for simple tasks
• -m auto: Smart routing (default) — auto-selects Flash or Pro based on complexity

3. Critical Behavioral Notes

Approval Mode Behavior: --approval-mode yolo auto-approves tool calls but does NOT prevent planning prompts. Gemini may still present plans and ask "Does this plan look good?" Use forceful language:

• "Apply now"
• "Start immediately"
• "Do this without asking for confirmation"

Note: --yolo / -y is deprecated. Use --approval-mode yolo instead. Other modes: default, auto_edit.

Rate Limits: Free tier limits apply. CLI auto-retries with exponential backoff. Expect messages like "quota will reset after Xs".

4. Output Processing

For JSON output (-o json), parse:

{
  "response": "actual content",
  "stats": {
    "models": { "tokens": {...} },
    "tools": { "byName": {...} }
  }
}

Quick Reference Commands

Code Generation

gemini "Create [description] with [features]. Output complete file content." --approval-mode yolo -o text

Code Review

gemini "Review [file] for: 1) features, 2) bugs/security issues, 3) improvements" -o text

Bug Fixing

gemini "Fix these bugs in [file]: [list]. Apply fixes now." --approval-mode yolo -o text

Test Generation

gemini "Generate [Jest/pytest] tests for [file]. Focus on [areas]." --approval-mode yolo -o text

Documentation

gemini "Generate JSDoc for all functions in [file]. Output as markdown." --approval-mode yolo -o text

Architecture Analysis

gemini "Use codebase_investigator to analyze this project" -o text

Web Research

gemini "What are the latest [topic]? Use Google Search." -o text

Faster Model (Simple Tasks)

gemini "[prompt]" -m gemini-2.5-flash -o text

Error Handling

Rate Limit Exceeded

• CLI auto-retries with exponential backoff
• Use -m gemini-2.5-flash for lower priority tasks (different quota)
• Use Auto routing (default) to let the system optimize model selection
• Run in background for long operations

Command Failures

• Check JSON output for detailed error stats
• Verify Gemini is authenticated: gemini --version
• Check ~/.gemini/settings.json for config issues

Validation After Generation

Always verify Gemini's output:

• Check for security vulnerabilities (XSS, injection)
• Test functionality matches requirements
• Review code style consistency
• Verify dependencies are appropriate

Integration Workflow

Standard Generate-Review-Fix Cycle

# 1. Generate
gemini "Create [code]" --approval-mode yolo -o text

# 2. Review (Gemini reviews its own work)
gemini "Review [file] for bugs and security issues" -o text

# 3. Fix identified issues
gemini "Fix [issues] in [file]. Apply now." --approval-mode yolo -o text

Background Execution

For long tasks, run in background and monitor:

gemini "[long task]" --approval-mode yolo -o text 2>&1 &
# Monitor with BashOutput tool

Gemini's Unique Capabilities

These tools are available only through Gemini:

1. google_web_search - Real-time internet search via Google
2. codebase_investigator - Deep architectural analysis (experimental agent, may require opt-in)
3. save_memory - Cross-session persistent memory

Model Selection

Model	Use Case
auto (default)	Smart routing — auto-selects Flash or Pro based on task complexity
gemini-2.5-pro	Complex reasoning tasks
gemini-2.5-flash	Quick tasks, lower latency
gemini-3-pro-preview	Latest capabilities (requires Google AI Ultra or paid API key)
gemini-3-flash-preview	Latest Flash model (requires Preview Features enabled)

Configuration

Project Context (Optional)

Create .gemini/GEMINI.md in project root for persistent context that Gemini will automatically read.

Session Management

List sessions: gemini --list-sessions
Resume session: echo "follow-up" | gemini -r [index] -o text

See Also

• reference.md - Complete command and flag reference
• templates.md - Prompt templates for common operations
• patterns.md - Advanced integration patterns
• tools.md - Gemini's built-in tools documentation