Nano Banana Image Generation (MCP)

Generate and edit images directly via the Nano Banana MCP server tools. No Gemini CLI dependency.

Upstream reference: https://github.com/gemini-cli-extensions/nanobanana

When to Use This Skill

ALWAYS use this skill when the user:

• Asks for any image, graphic, illustration, or visual
• Wants a thumbnail, featured image, or banner
• Requests icons, diagrams, or patterns
• Asks to edit, modify, or restore a photo
• Uses words like: generate, create, make, draw, design, visualize

Do NOT attempt to generate images through any other method.

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Health Check

Before first use, verify prerequisites:

1. Node.js >= 18 — required to run the MCP server
2. API key set — GEMINI_API_KEY or NANOBANANA_API_KEY environment variable
3. MCP server available — the nanobanana MCP tools should appear in your tool list

If MCP tools are not available, the plugin may need reinstalling. See references/troubleshooting.md.

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Tool Selection

User Request	MCP Tool
"generate an image of..."	generate_image
"create an app icon"	generate_icon
"draw a flowchart of..."	generate_diagram
"fix this old photo"	restore_image
"edit this image"	edit_image
"create a repeating texture"	generate_pattern
"make a comic strip"	generate_story

Quick Usage

Call the MCP tools directly with structured parameters:

Generate Images (default: 3 images)

Tool: generate_image
Parameters:
  prompt: "a sunset over mountains, photorealistic"
  outputCount: 3

Edit Existing Image

Tool: edit_image
Parameters:
  prompt: "change the background to a beach scene"
  file: "/absolute/path/to/image.jpg"

Generate App Icons

Tool: generate_icon
Parameters:
  prompt: "coffee cup logo"
  sizes: [64, 128, 256, 512]
  type: "app-icon"
  style: "modern"
  corners: "rounded"

Generate Diagram

Tool: generate_diagram
Parameters:
  prompt: "microservices architecture for e-commerce platform"
  type: "architecture"
  style: "professional"
  complexity: "detailed"

For full parameter reference for all 7 tools, see references/commands.md.

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Defaults

• File paths: Always resolve file paths to absolute paths before passing to any MCP tool. The MCP server runs in a different working directory, so relative paths will fail.
• outputCount: For generate_image, always use 3 unless user specifies otherwise. Other tools have their own count semantics (e.g., generate_icon uses sizes, generate_story uses steps).
• Model: gemini-3.1-flash-image-preview (override via NANOBANANA_MODEL env var)
• Output: Images saved to ./nanobanana-output/ in current directory

Presenting Results

After generation completes:

1. List contents of ./nanobanana-output/ to find generated files
2. Present the most recent image(s) to the user using the Read tool
3. Offer to regenerate with variations if needed

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Refinements and Iterations

When the user asks for changes:

• "Try again" / "Give me options": Call generate_image again with outputCount: 3
• "Make it more [adjective]": Adjust prompt and regenerate
• "Edit this one": Call edit_image with the file path and edit instructions
• "Different style": Add style to the styles array parameter

Prompt Tips

1. Be specific: Include style, mood, colors, composition details
2. Add "no text": If you don't want text rendered in the image
3. Reference styles: "editorial photography", "flat illustration", "3D render", "watercolor"
4. Specify aspect ratio: Include "wide 16:9" or "square" in the prompt description

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For image quality guidelines (style compliance, text accuracy, story consistency), see references/generation-guidelines.md. For error troubleshooting, see references/troubleshooting.md.