Gemini CLI Integration

Always run through subagents for better iteration and summarization. Make the subagent always ask Gemini to provide evidence, and make the subagent verify the findings before summarizing for the main agent.

Quick Reference

bash

# Basic one-shot query (non-interactive mode)
gemini "Explain this codebase architecture"

# Specify model
gemini -m gemini-3-flash-preview "Complex analysis task"
gemini -m gemini-2.5-flash "Standard analysis task"
gemini -m gemini-2.5-pro "Deep reasoning task"

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

# Multi-line prompt using heredoc
gemini <<'__GEMINI_PROMPT__'
Analyze this codebase for security vulnerabilities.
Focus on: SQL injection, XSS, authentication issues
__GEMINI_PROMPT__

# Output formats
gemini -o json "query"
gemini -o text "query"        # default
gemini -o stream-json "query"

Available Models

Gemini 3 (Preview)

•gemini-3-flash-preview - Best for agentic coding (78% SWE-bench), 1/4 cost of Pro.
•gemini-3-pro-preview - Most powerful for multimodal understanding and deep reasoning.

Gemini 2.5 (GA)

•gemini-2.5-flash - Stable, fast
•gemini-2.5-pro - Balanced performance for complex tasks
•gemini-2.5-flash-lite - Lowest latency and cost

Subagent Delegation Pattern

CRITICAL: Always delegate Gemini tasks to a subagent using the Task tool for multiple retry attempts, better summarization, and error handling.

Pattern: Using Task Tool with Gemini

bash

Task(
  subagent_type: "general-purpose",
  description: "Analyze codebase with Gemini",
  prompt: "Use the gemini-cli skill to analyze /path/to/project.
  Focus on security vulnerabilities and performance issues.
  See references/prompt_patterns.md for effective prompts.
  Ask Gemini to provide evidence for findings.
  Verify findings before summarizing key points in bullet form."
)

Pattern: Second Opinion

bash

Task(
  subagent_type: "general-purpose",
  description: "Get Gemini second opinion",
  prompt: "Use gemini-cli skill to get Gemini's critique of the analysis.
  See references/prompt_patterns.md for second opinion prompts.
  Highlight disagreements or missing considerations."
)

When to Use Gemini vs Claude

Use Gemini for	Use Claude for
Massive codebase review (>100k tokens)	Quick code questions
Cross-validating critical analysis	Small file analysis
Multi-file architecture analysis	Interactive coding assistance
Tasks exceeding Claude's context	Tasks requiring file edits
	Tasks requiring follow-up questions

Model Selection Guide

•Production workloads: gemini-2.5-flash (stable, any endpoint)
•Cutting-edge agentic coding: gemini-3-flash-preview (requires global endpoint)
•Complex reasoning: gemini-2.5-pro or gemini-3-pro-preview
•High-volume simple queries: gemini-2.5-flash-lite

Troubleshooting

Model not available:

•Gemini 3 models require -preview suffix and GOOGLE_CLOUD_LOCATION=global
•Fall back to Gemini 2.5 models which work on all endpoints

Slow responses: Large context takes time. Consider narrowing scope or use gemini-2.5-flash-lite.