Gemini CLI

Interact w/ Google's Gemini CLI locally. Run queries, get responses, compare outputs.

Prerequisites

Gemini CLI must be installed & configured:

1. Install: https://github.com/google-gemini/gemini-cli
2. Auth: Run gemini & sign in w/ Google account
3. Verify: gemini --version

When to Use

• User asks to "run/ask/use gemini"
• Compare Claude vs Gemini responses
• Get second AI opinion
• Delegate task to Gemini

Usage

IMPORTANT: Use -p flag for non-interactive (headless) one-shot queries. Without -p, gemini opens interactive mode which hangs in automation.

# One-shot query (MUST use -p for non-interactive)
gemini -p "Your prompt"

# Specific model
gemini -p "prompt" -m gemini-3-pro

# JSON output
gemini -p "prompt" -o json

# Auto-approve tool use (-y is deprecated)
gemini --approval-mode=yolo -p "prompt"

# File analysis
cat file.txt | gemini -p "Analyze this"

Models

Alias	Use case
auto	DEFAULT — routes per prompt (simple → Flash, complex → 3 Pro)
pro	Force Gemini 3 Pro (best all-round)
flash / flash-lite	Fast, lightweight tasks (3.5 Flash GA rolling out as auto default)

Omit -m to use auto routing. Aliases beat pinned model ids — they track upstream model swaps. Pin a full id (e.g. gemini-3-pro) only when the user names one.

CLI Options

Flag	Desc
-p	Required for headless. Non-interactive prompt
-m	Model selection
-o	Output: text/json/stream-json
--approval-mode=yolo	Auto-approve all actions (-y is deprecated)
-d	Debug mode
-s	Sandbox mode
-r	Resume session
-i	Execute prompt then continue interactive

Comparison Workflow

1. Provide Claude's response first
2. Run same query via gemini -p "prompt"
3. Present both for comparison

Best Practices

• Always use -p for automation/one-shot queries
• Quote prompts w/ double quotes
• Use -o json for parsing
• Pipe files for context