Agent skill

nano-banana

REQUIRED for all image generation requests. Generate and edit images using Nano Banana (Gemini CLI). Handles blog featured images, YouTube thumbnails, icons, diagrams, patterns, illustrations, photos, visual assets, graphics, artwork, pictures. Use this skill whenever the user asks to create, generate, make, draw, design, or edit any image or visual content.

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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/nano-banana

SKILL.md

Nano Banana Image Generation

Generate professional images via the Gemini CLI's nanobanana extension.

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.

Command Selection

User Request Command
"make me a blog header" /generate
"create an app icon" /icon
"draw a flowchart of..." /diagram
"fix this old photo" /restore
"remove the background" /edit
"create a repeating texture" /pattern
"make a comic strip" /story

Available Commands

Note: Always use the --yolo flag to automatically approve all tool actions and the --allowed-mcp-server-names nanobanana flag to auto-enable the required MCP.

Command Use Case
gemini "/generate 'prompt'" Text-to-image generation
gemini "/edit file.jpg 'instruction'" Modify existing image
gemini "/restore old_photo.jpg 'fix scratches'" Repair damaged photos
gemini "/icon 'description'" App icons, favicons, UI elements
gemini "/diagram 'description'" Flowcharts, architecture diagrams
gemini "/pattern 'description'" Seamless textures and patterns
gemini "/story 'description'" Sequential/narrative images
gemini "/nanobanana prompt" Natural language interface

Command Options

  • --yolo - Required. Auto-approve all tool actions (no confirmation prompts)
  • --allowed-mcp-server-names nanobanana Required.

Prompt Options

  • --count=N - Generate N variations (1-8)
  • --preview - Auto-open generated images
  • --styles="style1,style2" - Apply artistic styles
  • --format=grid|separate - Output arrangement

Common Sizes

Use Case Dimensions Notes
YouTube thumbnail 1280x720 --aspect=16:9
Blog featured image 1200x630 Social preview friendly
Square social 1080x1080 Instagram, LinkedIn
Twitter/X header 1500x500 Wide banner
Vertical story 1080x1920 --aspect=9:16

Model Selection

Default: gemini-2.5-flash-image (~$0.04/image)

For higher quality (4K, better reasoning):

bash
export NANOBANANA_MODEL=gemini-3-pro-image-preview

Blog Featured Image Example

bash
# Modern illustration style
gemini --allowed-mcp-server-names nanobanana --yolo "/generate 'modern flat illustration of developer coding at laptop, purple and blue gradient background, minimalist style, no text' --preview --count=3"

Icon Generation

bash
gemini --allowed-mcp-server-names nanobanana --yolo "/icon 'minimalist app logo for productivity tool' --sizes='64,128,256,512' --type='app-icon' --corners='rounded'"

Diagram Generation

bash
gemini --allowed-mcp-server-names nanobanana --yolo "/diagram 'user authentication flow with OAuth' --type='flowchart' --style='modern'"

Output Location

All generated images are saved to ./nanobanana-output/ in the current directory.

Presenting Results

After generation completes:

  1. List contents of ./nanobanana-output/ to find generated files.
  2. Verify using file <path> that the image is valid and the image type matches the file extension. Rename the file if the extension doesn't match.
  3. Present the most recent image(s) to the user.
  4. Offer to regenerate with variations if needed.

Refinements and Iterations

When the user asks for changes:

  • "Try again" / "Give me options": Regenerate with --count=3
  • "Make it more [adjective]": Adjust prompt and regenerate
  • "Edit this one": Use gemini --allowed-mcp-server-names nanobanana --yolo "/edit nanobanana-output/filename.jpg 'adjustment'"
  • "Different style": Add --styles="requested_style" to the command

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 context: "wide banner", "square thumbnail", "vertical story"

Troubleshooting

Problem Solution
Extension not found Run install command from setup section
Quota exceeded Wait for reset or switch to flash model
Image generation failed Check prompt for policy violations, simplify request
Output directory missing Will be created automatically on first run

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