Nano Banana 2 - AI Image Generation

Generate stunning 4K images, edit photos, and create graphics with perfect text rendering using Google's latest Gemini 3.1 Flash Image model via MCP.

When to Use

Invoke when user:

• Asks to "generate an image" or "create a picture"
• Wants to "edit this photo" or "modify this image"
• Needs graphics with text (logos, infographics, diagrams)
• Requests "consistent characters" across multiple images
• Says "visualize this" or "make me a [visual thing]"

Prerequisites

1. Gemini API Key

Get a free API key from Google AI Studio:

1. Sign in with Google account
2. Click "Get API Key" → "Create API Key"
3. Copy and save securely

2. MCP Server Setup

Recommended: NanoBanana-MCP (uses Gemini 3.1 Flash Image for highest quality)

# Quick install via Claude Code CLI
claude mcp add nano-banana --env GEMINI_API_KEY=your-key-here -- npx -y nanobanana-mcp

Or add to ~/.claude/settings.json manually:

{
  "mcpServers": {
    "nano-banana": {
      "command": "npx",
      "args": ["-y", "nanobanana-mcp"],
      "env": {
        "GEMINI_API_KEY": "your-api-key-here"
      }
    }
  }
}

Alternative: Nano-Banana-MCP by ConechoAI (Gemini 2.0 Flash - faster, lower cost)

{
  "mcpServers": {
    "nano-banana": {
      "command": "npx",
      "args": ["nano-banana-mcp"],
      "env": {
        "GEMINI_API_KEY": "your-api-key-here"
      }
    }
  }
}

Available Tools

Once MCP is configured, these tools become available:

Core Tools

Tool	Purpose	Key Parameters
gemini_generate_image	Create new images from text prompts	prompt, model, aspectRatio, imageSize
gemini_edit_image	Modify existing images with instructions	imagePath, instructions, model
continue_editing	Refine the last generated image	instructions
get_image_history	List all generated images in session	-

Model Options

Model ID	Description
gemini-3.1-flash-image-preview	Default. Highest quality, 4K support, best text rendering (Nano Banana 2)
gemini-3-pro-image-preview	Previous generation, still high quality
gemini-2.0-flash-exp	Faster generation, good quality, lower cost

Image Size (Gemini 3.1 / 3 only)

Size	Use Case
4K	Final assets, print, marketing materials
2K	Balanced quality and speed
1K	Fast iteration, prototyping

Advanced Features

Feature	Capability
4K Output	Up to 5632×3072 pixels
Text Rendering	Accurate text in images (signs, labels, UI)
Multi-Image Composition	Combine up to 14 reference images
Character Consistency	Maintain same character across 5+ images
Google Search Grounding	Real-world accurate imagery

Prompting Best Practices

Structure Your Prompts

[Subject] + [Style] + [Details] + [Technical Specs]

Example:

"A cozy coffee shop interior, watercolor illustration style, warm lighting, wooden furniture, steaming cup on table, 4K resolution, soft morning light through windows"

For Best Results

1. Be Specific - Include colors, materials, lighting, mood
2. Specify Style - "photorealistic", "oil painting", "3D render", "anime"
3. Add Context - Time of day, weather, setting
4. Request Resolution - "4K", "high resolution", "detailed"

Precision Mode (JSON Prompting)

For high-stakes work requiring exact reproducibility, use structured JSON schemas.

When to Activate

Trigger phrases:

• "I need exact control over..."
• "Create a product shot for [brand]..."
• "Generate a UI mockup..."
• "Make an infographic showing..."
• "I want to iterate on just the lighting..."
• "A/B test different versions..."

Three Schema Types

Type	Use Case	Key Controls
marketing_image	Product shots, hero images	subject, props, lighting, camera, brand locks
ui_builder	App screens, dashboards	tokens, screens, containers, components
diagram_spec	Flowcharts, infographics	nodes, edges, data constraints

The Translator Workflow

1. Describe - User explains what they want in plain English
2. Clarify - Claude asks targeted questions for missing fields
3. Generate - Claude outputs structured JSON schema
4. Review - User checks key fields match intent
5. Render - JSON converts to precise prompt for Nano Banana 2
6. Iterate - Modify specific fields, re-render (scoped changes)

Example: Product Shot

User: "I need a hero shot for Aurora Lime seltzer"

Claude asks: "For the Aurora Lime hero shot:

1. Can size? (12oz standard?)
2. Props? (lime slices, ice, condensation?)
3. Background style? (solid color, gradient, bokeh?)
4. Lighting mood? (bright/refreshing or moody/premium?)"

Result: Structured JSON with exact specifications that can be iterated field-by-field.

Scoped Edits (The Key Unlock)

JSON enables changing ONE thing without regenerating everything:

Change	What Stays Fixed
Swap lighting direction	Subject, props, background
Try different camera angle	Lighting, props, environment
Change background color	Subject geometry, lighting setup
Add/remove props	Everything else

Reference Docs

• references/json-prompting.md - Full JSON prompting guide
• references/translator-prompt.md - Translator system prompt
• references/schemas/ - Template schemas for each type
• references/examples-json.md - Filled-out examples

Text in Images

Nano Banana 2 excels at text rendering:

"A vintage movie poster for 'COSMIC ADVENTURE' with bold retro typography, starfield background, astronaut silhouette, 1970s sci-fi aesthetic"

Character Consistency

For consistent characters across images:

1. Generate initial character with detailed description
2. Use history:0 reference in subsequent prompts
3. Describe scene changes while referencing original

First: "A young woman with red curly hair, freckles, green eyes, wearing a blue jacket"
Then: "The same woman from history:0, now sitting at a café, reading a book"

Workflow Examples

Basic Image Generation

User: "Create an image of a futuristic city at sunset"

Claude uses: gemini_generate_image
Prompt: "Futuristic cityscape at golden hour sunset, towering glass skyscrapers with holographic advertisements, flying vehicles, warm orange and purple sky, photorealistic, 4K resolution, cinematic lighting"

Photo Editing

User: "Edit this photo to make it look like winter"

Claude uses: gemini_edit_image
Input: [user's image path]
Instructions: "Transform to winter scene: add snow on ground and surfaces, frost on windows, visible breath, overcast sky, cool blue color grading"

Iterative Refinement

User: "Make the lighting warmer"

Claude uses: continue_editing
Instructions: "Adjust lighting to warmer tones, add golden hour glow, enhance orange/yellow highlights, softer shadows"

Output Management

Images save to: ~/Documents/nanobanana_generated/

Naming format: generated-[timestamp]-[id].png

Security Notes

• API keys stored locally in environment variables
• Never committed to version control
• Images processed locally, not stored on external servers
• Use .env files for key management in projects

Model Comparison

Model	Speed	Quality	Cost	Best For
gemini-3.1-flash-image-preview	Fast	Highest (4K)	Moderate	Final assets, print, marketing
gemini-3-pro-image-preview	Slower	High (4K)	Higher	Previous-gen fallback
gemini-2.0-flash-exp	Fastest	Good	Lower	Prototyping, iteration, drafts

Troubleshooting

Issue	Solution
"API key invalid"	Verify key at AI Studio
"Rate limited"	Wait 60s, or upgrade API tier
"MCP not connected"	Restart Claude Code, check config syntax
"Image not saving"	Check write permissions on output directory

Integration

Works well with:

• Artifacts Builder - Generate images for HTML artifacts
• Process Mapper - Create diagram visuals
• Research to Essay - Add illustrations to content

References

• references/prompting-guide.md - Detailed prompting techniques
• references/examples.md - Sample prompts by category