Gemini CLI

Gemini CLI Integration

Gemini CLI provides access to Google's Gemini models with 1 million token context windows directly from the terminal. Use it as a complementary tool for tasks where extended context or alternative perspectives add value.

Core Use Cases

1. Large codebase analysis - Analyze entire repositories that exceed Claude's context
2. Deep thinking tasks - Extended reasoning on complex architectural decisions
3. Second opinions - Cross-validate Claude's analysis on critical problems
4. Bulk file processing - Process multiple files in a single context

Quick Reference

# Basic one-shot query
gemini "Explain this codebase architecture"

# Interactive mode (continue conversation)
gemini -i "Start analyzing this project"

# Auto-approve file operations (use carefully)
gemini --approval-mode yolo "Refactor all deprecated API calls"

# Specify model explicitly
gemini -m gemini-2.5-pro "Complex analysis task"

# Include additional directories
gemini --include-directories ./libs,./shared "Analyze dependencies"

# Resume previous session
gemini --resume latest
gemini --resume 3

# List available sessions
gemini --list-sessions

# Use EOF pattern for multi-line prompt input
gemini <<'__GEMINI_PROMPT__'
... your prompt including any EOF, code fences, rich formatting, etc ...
__GEMINI_PROMPT__

Workflow Patterns

Pattern 1: Codebase Analysis

Run scripts/analyze_codebase.sh for comprehensive codebase review:

./scripts/analyze_codebase.sh /path/to/project "Focus on security vulnerabilities"

Or manually:

cd /path/to/project
gemini "Analyze this codebase. Focus on:
1. Architecture patterns and anti-patterns
2. Code quality issues
3. Security concerns
4. Performance bottlenecks
5. Improvement recommendations"

Pattern 2: Second Opinion

When Claude has provided an analysis, seek Gemini's perspective:

gemini "I received this analysis from another AI:
---
[paste Claude's analysis]
---

Review this analysis critically. Identify:
- Points you agree with and why
- Points you disagree with and alternatives
- Gaps or missing considerations
- Additional recommendations"

Pattern 3: Deep Reasoning

For complex architectural decisions requiring extended thinking:

gemini -i "I need deep analysis on migrating from monolith to microservices.

Context:
- Current: Java monolith, 500k LOC, PostgreSQL
- Team: 15 developers, 3 teams
- Traffic: 10k req/sec peak

Think through:
1. Service boundary identification
2. Data decomposition strategy  
3. Migration sequence
4. Risk assessment
5. Timeline estimation"

Pattern 4: Interactive Exploration

For iterative analysis requiring conversation:

gemini -i "Let's explore the design options for this system"

Continue with follow-up questions in the interactive session.

Approval Modes

Recommendation: Use default mode for analysis. Use auto_edit for refactoring tasks with review. Reserve yolo for well-understood, reversible operations.

Output Formats

# Standard text (default, best for reading)
gemini -o text "query"

# JSON (for programmatic processing)
gemini -o json "query"

# Streaming JSON (for real-time integration)
gemini -o stream-json "query"

Session Management

Gemini maintains conversation sessions that can be resumed:

# List available sessions
gemini --list-sessions

# Resume most recent session
gemini --resume latest

# Resume specific session by index
gemini --resume 5

# Delete a session
gemini --delete-session 3

MCP Server Integration

Gemini supports Model Context Protocol (MCP) servers for extended capabilities:

# Manage MCP servers
gemini mcp

# Allow specific MCP servers
gemini --allowed-mcp-server-names server1,server2 "query"

Best Practices

1. Scope appropriately - Don't dump entire monorepos; focus on relevant modules
2. Provide context - Include problem background, constraints, and goals
3. Be specific - Vague queries yield vague responses
4. Use interactive mode - For exploratory analysis requiring iteration
5. Review before auto-approve - Understand what yolo mode will execute
6. Combine perspectives - Use Gemini's analysis alongside Claude's for critical decisions

When to Use Gemini vs Claude

Troubleshooting

Context too large: Split analysis into focused modules rather than entire repository.

Session lost: Use --list-sessions to find previous sessions, --resume to continue.

Slow responses: Large context requires processing time. Consider narrowing scope.

API errors: Verify Gemini CLI authentication with gemini --version and check Google Cloud credentials.

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