Gemini Flash Image 2.5 Tool (Nano Banana)

A tool for generating and editing images using Google's Gemini 2.5 Flash Image API (affectionately known as "Nano Banana").

Includes both a Python CLI tool and a Model Context Protocol (MCP) server for integration with AI assistants like Claude Code.

Features

• Text-to-Image Generation: Create images from text prompts

• Image Editing: Modify existing images with natural language instructions

• Multi-Image Composition: Combine multiple images into one

• Flexible Aspect Ratios: Support for 10 different aspect ratios

• Character Consistency: Maintain character appearance across multiple generations

• MCP Server: Integrate with Claude Code and other MCP clients

• Command-Line Interface: Easy-to-use CLI for quick operations

• Python API: Use as a library in your own projects

Related MCP server: OpenRouter Image MCP Server

Installation

Option 1: MCP Server (Recommended for AI Assistants)

Simplest Install (using npx)

For Claude Code MCP configuration, you can reference the package directly via GitHub:

Add to your MCP settings (~/.config/claude/claude_desktop_config.json):

{
  "mcpServers": {
    "gemini-image": {
      "command": "npx",
      "args": ["-y", "github:brunoqgalvao/gemini-image-mcp-server"],
      "env": {
        "GEMINI_API_KEY": "your_api_key_here"
      }
    }
  }
}

Then restart Claude Code! The generate_image tool will be available instantly.

Local Install

# Clone the repository
git clone https://github.com/brunoqgalvao/gemini-image-mcp-server.git
cd gemini-image-mcp-server

# Run the installer
./install.sh

The installer will:

• Install Node.js dependencies

• Create a .env file from template

• Run validation tests

• Show you the MCP configuration to add to Claude Code

Manual Install

1. Clone or download this repository

2. Install Node.js dependencies:

npm install

3. Get your API key from Google AI Studio

4. Create a .env file in the project directory:

GEMINI_API_KEY=your_api_key_here

5. Configure your MCP client (e.g., Claude Code):

For macOS/Linux - Add to ~/.config/claude/claude_desktop_config.json:

{
  "mcpServers": {
    "gemini-image": {
      "command": "node",
      "args": ["/absolute/path/to/agent-dispatcher/index.js"],
      "env": {
        "GEMINI_API_KEY": "your_api_key_here"
      }
    }
  }
}

For Windows - Add to %APPDATA%\Claude\claude_desktop_config.json:

{
  "mcpServers": {
    "gemini-image": {
      "command": "node",
      "args": ["C:\\absolute\\path\\to\\agent-dispatcher\\index.js"],
      "env": {
        "GEMINI_API_KEY": "your_api_key_here"
      }
    }
  }
}

6. Restart Claude Code or your MCP client

Installing on Another Computer

Easiest way - Just use npx! On any computer with Node.js:

Add to Claude Code MCP settings:

{
  "mcpServers": {
    "gemini-image": {
      "command": "npx",
      "args": ["-y", "github:brunoqgalvao/gemini-image-mcp-server"],
      "env": {
        "GEMINI_API_KEY": "your_api_key_here"
      }
    }
  }
}

No cloning needed! npx will fetch and run it automatically.

Alternative: Local installation

# Clone and install
git clone https://github.com/brunoqgalvao/gemini-image-mcp-server.git
cd gemini-image-mcp-server
./install.sh

Option 2: Python CLI Tool

1. Clone or download this repository

2. Install Python dependencies:

pip install -r requirements.txt

3. Get your API key from Google AI Studio

4. Create a .env file in the project directory:

GEMINI_API_KEY=your_api_key_here

Usage

MCP Server

Once configured, the generate_image tool will be available in your MCP client:

Parameters:

• prompt (required): Text description of the image to generate or edits to make

• output_path (required): Path where the image will be saved (must end in .png)

• input_images (optional): Array of paths to input images for editing/composition

• aspect_ratio (optional): One of: 1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9

• image_only (optional): Set to true for image-only output without text

Example usage in Claude Code:

"Generate a sunset over mountains and save it to sunset.png"

The MCP server will handle the API call and save the image automatically.

Command Line

Basic text-to-image generation:

python gemini_image_tool.py "A cat eating a banana in space" -o cat_banana.png

Edit an existing image:

python gemini_image_tool.py "Remove the background" -i photo.jpg -o edited.png

Compose multiple images:

python gemini_image_tool.py "Combine these into a collage" -i img1.jpg -i img2.jpg -o collage.png

Specify aspect ratio:

python gemini_image_tool.py "A cinematic landscape" -o wide.png --aspect-ratio 21:9

Image-only output (no text response):

python gemini_image_tool.py "A red apple" -o apple.png --image-only

Save full API response:

python gemini_image_tool.py "A sunset" -o sunset.png --save-json response.json

Python API

from gemini_image_tool import GeminiImageTool

# Initialize the tool
tool = GeminiImageTool(api_key="your_api_key_here")

# Generate an image
result = tool.generate_content(
    prompt="A futuristic city at night",
    aspect_ratio="16:9",
    output_path="city.png"
)

# Edit an image
result = tool.generate_content(
    prompt="Make the sky purple",
    input_images=["city.png"],
    output_path="city_purple.png"
)

# Combine multiple images
result = tool.generate_content(
    prompt="Create a before/after comparison",
    input_images=["before.jpg", "after.jpg"],
    aspect_ratio="2:1",
    output_path="comparison.png"
)

Available Aspect Ratios

• 1:1 - Square (default)

• 2:3 - Portrait

• 3:2 - Landscape

• 3:4 - Portrait

• 4:3 - Landscape

• 4:5 - Portrait

• 5:4 - Landscape

• 9:16 - Vertical (social media)

• 16:9 - Widescreen

• 21:9 - Cinematic

Supported Image Formats

Input: JPG, JPEG, PNG, WebP, GIF Output: PNG

Pricing

As of 2025, Gemini 2.5 Flash Image is priced at:

• $30.00 per 1 million output tokens

• Each image = 1290 output tokens

• Cost per image: ~$0.039

Use Cases

• E-commerce: Product photography and variations

• Content Creation: Social media graphics, blog images

• Marketing: Ad creatives, promotional materials

• Storytelling: Consistent character illustrations

• Photo Editing: Background removal, color correction, object removal

• Design: Logo variations, mockups, concept art

Command-Line Arguments

positional arguments:
  prompt                Text prompt for image generation/editing

optional arguments:
  -h, --help            Show help message
  -i INPUT, --input INPUT
                        Input image file path (can be specified multiple times)
  -o OUTPUT, --output OUTPUT
                        Output image file path (default: output.png)
  -a ASPECT_RATIO, --aspect-ratio ASPECT_RATIO
                        Output aspect ratio (default: 1:1)
  --image-only          Request image-only output (no text response)
  --api-key API_KEY     Google AI API key (or set GEMINI_API_KEY env variable)
  --save-json SAVE_JSON
                        Save full API response to JSON file

Error Handling

The tool includes comprehensive error handling for:

• Missing API keys

• Invalid image paths

• Unsupported image formats

• Invalid aspect ratios

• API request failures

• Network errors

Notes

• All generated images include a SynthID watermark (added by Google)

• The model benefits from Gemini's world knowledge for enhanced generation

• Character consistency works best with clear, descriptive prompts

• For best results, be specific in your prompts

Documentation

For more information about Gemini 2.5 Flash Image:

• Official Documentation

• Google Developers Blog

License

This tool is provided as-is for use with the Gemini API. See Google's terms of service for API usage restrictions.