How to Use Gemini CLI: A Comprehensive Guide

Overview

Gemini CLI is a conversational AI assistant similar to Claude Code but powered by Google's Gemini model. After extensive testing, here's what you need to know.

Installation & Version

• Current Version: 0.1.3
• Installation: Available via Homebrew (/opt/homebrew/bin/gemini)
• Language: Interface is in Spanish by default

Basic Usage

Command Structure

gemini [options] [prompt]
echo "your message" | gemini [options]

Key Options

• -m, --model: Select model (default: gemini-2.5-pro)
• -p, --prompt: Append prompt to stdin input
• -s, --sandbox: Run in sandbox mode
• -d, --debug: Enable debug mode
• -a, --all_files: Include all files in context
• -y, --yolo: Auto-accept all actions (dangerous)
• -c, --checkpointing: Enable file edit checkpointing

What Gemini CLI is Good For

✅ Strengths

1. Code Analysis: Excellent at identifying bugs and potential issues
2. Natural Language Understanding: Handles conversational requests well
3. Explanations: Provides clear, detailed explanations of concepts
4. Context Awareness: Remembers conversation context and file contents
5. File Operations: Can read, analyze, and modify files effectively
6. Planning: Good at breaking down complex tasks into steps

❌ Limitations

1. Language Barrier: Default Spanish interface can be confusing
2. File Execution: Doesn't seem to execute file modifications as smoothly as Claude Code
3. Interactive Mode: Less polished interactive experience compared to Claude Code
4. Tool Integration: Limited compared to Claude Code's extensive tool ecosystem
5. Error Handling: Less robust error recovery mechanisms

Comparison with Claude Code

Feature	Gemini CLI	Claude Code
Code Analysis	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐
File Operations	⭐⭐⭐⭐	⭐⭐⭐⭐⭐
Interactive Experience	⭐⭐⭐	⭐⭐⭐⭐⭐
Tool Integration	⭐⭐⭐	⭐⭐⭐⭐⭐
Error Handling	⭐⭐⭐	⭐⭐⭐⭐⭐
Language Support	⭐⭐	⭐⭐⭐⭐⭐

Usage Rules and Best Practices

1. Input Methods

# Direct prompt
gemini -p "Analyze this code for bugs"

# Pipe input
echo "Fix the division by zero error" | gemini

# Combined approach
echo "Review this file" | gemini -p "Focus on security issues"

2. Context Management

• Use -a, --all_files sparingly as it can overwhelm the context
• Provide clear, specific prompts for better results
• Break complex tasks into smaller, focused requests

3. Safety Considerations

• Never use -y, --yolo flag in production environments
• Always review suggested changes before applying them
• Use --sandbox mode for testing potentially dangerous operations

4. Model Selection

• Default gemini-2.5-pro is suitable for most tasks
• Consider model capabilities when choosing alternatives

Common Use Cases

Code Review

echo "Review this JavaScript file for bugs and improvements" | gemini -p "Focus on:"

Bug Fixing

echo "Fix the identified issues in the calculator functions" | gemini

Documentation

echo "Generate JSDoc comments for all functions" | gemini -p "Include examples:"

Testing

echo "Create unit tests for the calculator functions" | gemini -p "Use Jest framework:"

When to Use Gemini CLI vs Claude Code

Use Gemini CLI When:

• You need a second opinion on code analysis
• Working with Google's ecosystem
• Prefer Gemini's reasoning style
• Want to compare AI model outputs

Use Claude Code When:

• Need robust file operations and tool integration
• Require extensive interactive capabilities
• Working on complex, multi-step tasks
• Need reliable error handling and recovery

Troubleshooting

Common Issues:

1. Spanish Interface: Currently no obvious way to change language
2. File Modifications: May not execute as expected - always verify changes
3. Context Limits: Large codebases may hit context limitations

Solutions:

• Use specific, targeted prompts
• Break large tasks into smaller chunks
• Verify all file modifications manually
• Use checkpointing (-c) for important edits

Conclusion

Gemini CLI is a capable AI assistant that excels at code analysis and explanations. While it has some limitations compared to Claude Code, it serves well as a complementary tool for getting different perspectives on code problems. The Spanish interface and less polished interactive experience are notable drawbacks, but the core AI capabilities are strong.

Recommendation: Use Gemini CLI as a secondary tool alongside Claude Code for comprehensive code analysis and review, but rely on Claude Code for primary development workflows.