generate-image

Image Generation with Nano Banana 2

Use the generate_image, edit_image, and continue_editing MCP tools from the nano-banana-2 server.

First-Time Setup

Before generating images, verify the API key is configured:

1. Call get_configuration_status to check if GEMINI_API_KEY is set.
2. If the key is missing, instruct the user to add it to their MCP server environment configuration:
   • In Claude Code settings or .claude/settings.json, add GEMINI_API_KEY to the server's env block.
   • The key can be obtained from Google AI Studio.

Prompting Best Practices

Write narrative paragraphs, NOT comma-separated keyword lists. Narrative prompts achieve ~94% coherence vs ~61% for keyword lists.

1. Start with image type: "Create an educational diagram showing...", "Generate a photorealistic photograph of...", "Design a flat-style icon depicting..."
2. Keep text in images short (<25 characters). Quote text exactly and describe font style.
3. Specify layout explicitly: side-by-side, top-to-bottom steps, centered with border, etc.
4. Skip quality boosters like "4k masterpiece", "highly detailed", "award-winning" — they add noise, not quality.
5. Be specific about what you want, not what you don't want. Positive descriptions work better than negations.

Defaults

• resolution: "1K" — good balance of quality and speed. Use "2K" or "4K" for print or detail-heavy images.
• aspectRatio: "1:1" — change to "16:9" for landscapes/banners, "9:16" for mobile/portrait.
• thinking: "minimal" — use "high" for complex scenes with spatial relationships or text rendering.
• returnInlineImage: Consider setting to false in Claude Code to avoid context window overflow. The image is still saved to disk and can be viewed by the user.
• outputMimeType: "image/png" for quality, "image/jpeg" for smaller files.
• numberOfImages: 1 — use 2-4 when exploring variations.

Workflow

1. Generate: Use generate_image with a well-crafted narrative prompt.
2. Review: Check the saved file path in the response.
3. Refine: Use continue_editing to make adjustments. Be specific about what to change.
4. Iterate: Each continue_editing call builds on the previous result.

Style Guidance

• Diagrams: Specify colors, label positions, arrow directions. Use thinking: "high" for complex layouts.
• Illustrations: Describe art style (flat, watercolor, line art), mood, and lighting.
• Infographics: Use numbered lists cautiously (>8 sequential items are unreliable). Numbers-only approach works best for long lists.
• Photos: Describe camera angle, lighting conditions, depth of field, and subject positioning.

Context Window Management

When generating images in Claude Code, set returnInlineImage: false to prevent base64 image data from filling the context window. The image is still saved to disk — just tell the user where to find it.