MCP server for AI image generation and editing with automatic prompt optimization and quality presets (fast/balanced/quality). Powered by Gemini (Nano Banana 2 & Pro).
AI Agentsagent-skillsai-toolsclaude-codecodexcursor
Installation
# Add to your Claude Code skills
git clone https://github.com/shinpr/mcp-image
README.md
MCP Image Generator 🍌
AI image generation and editing MCP server for Cursor, Claude Code, Codex, and any MCP-compatible tool — powered by Nano Banana 2 and Nano Banana Pro (Google Gemini).
An MCP server that turns simple text prompts into high-quality images. Unlike a simple API wrapper, this server automatically enhances your prompt and configures sensible defaults for generation — you don't need to learn prompt engineering or tune settings. Just describe what you want.
How It Works
You: "cat on a roof"
↓
Your AI assistant infers context
(purpose, style, mood, resolution...)
↓
MCP optimizes your prompt
(adds lighting, composition, atmosphere, artistic details)
↓
Image generation with smart defaults
(grounding, consistency, resolution — all configured automatically)
↓
High-quality image, zero effort
Your AI assistant interprets your intent — the style, purpose, and context behind your request. The MCP focuses on output quality by refining the prompt to meet a structured visual clarity standard and selecting appropriate generation settings. You just describe what you want.
The prompt optimizer uses a Subject–Context–Style framework (powered by Gemini 2.5 Flash) to fill in missing visual details — subject characteristics, environment, lighting, camera work — while preserving your original intent. It doesn't blindly add details: prompts that already meet the quality standard are left largely intact.
Example — what the optimizer does to a short prompt:
After optimization: "A sleek, midnight black cat, perched with poised elegance on the apex of a weathered, terracotta tile roof. Its emerald eyes, narrowed slightly, reflect the warm glow of a setting sun. Each individual tile is distinct, showing subtle variations in color and texture, with patches of moss clinging to the crevices. The cat's fur is sharply defined, catching the golden hour light, highlighting its sleek contours. In the background, the silhouettes of distant, old-world city buildings with ornate spires are softly blurred, bathed in a gradient of fiery orange, soft pink, and deep violet twilight. A gentle, ethereal mist begins to rise from the alleyways below, adding a touch of mystery. The composition is a medium shot, taken from a slightly low angle, emphasizing the cat's commanding presence against the vast sky. Photorealistic style, captured with a prime lens, wide aperture to create a beautiful bokeh, enhancing the depth of field."
Features
Built-in Prompt Optimization: Your simple prompt is automatically enriched with photographic and artistic details — lighting, composition, atmosphere — using Gemini 2.5 Flash. No prompt engineering skills required.
Three Quality Tiers: Choose between fast iteration, balanced quality, or maximum fidelity with Nano Banana 2 (Gemini 3.1 Flash Image) and Nano Banana Pro (Gemini 3 Pro Image). See Quality Presets.
Image Editing: Transform existing images with natural language instructions (image-to-image) while preserving original style and visual consistency.
High-Resolution Output: Up to 4K image generation for professional-grade output with superior text rendering and fine details.
Flexible Aspect Ratios: From square (1:1) to ultra-wide (21:9) and ultra-tall (1:8) formats.
Character Consistency: Maintain consistent character appearance across multiple generations — ideal for storyboards, product shots, and visual series.
Advanced Capabilities:
Google Search grounding for real-time factual accuracy
World knowledge for photorealistic depictions of historical figures, landmarks, and factual scenarios
Multi-image blending for composite scenes
Purpose-aware generation (e.g., "cookbook cover" produces different results than "social media post")
Multiple Output Formats: PNG, JPEG, WebP support.
Agent Skill: Image Generation Prompt Guide
This project also provides a standalone Agent Skill (SKILL.md) that teaches AI assistants to write better image generation prompts — no MCP server or API key required.
Note: This skill does not generate images itself. It teaches your AI assistant to write better prompts for tools that already have built-in image generation (e.g., Cursor's native image generation).
Based on the Subject-Context-Style framework, covering prompt structure, visual details (lighting, textures, camera angles), advanced techniques (character consistency, composition), and image editing. Works with any image model (Gemini, GPT Image, Flux, Stable Diffusion, Midjourney, etc.).
| | MCP Server | Agent Skill |
|---|---|---|
| Use when | Your AI tool does not have built-in image generation | Your AI tool already generates images natively |
| Requires | Gemini API key | Nothing |
| What it does | Generates images via Gemini API with automatic prompt optimization | Teaches the AI to write better prompts |
| Works with | MCP-compatible tools (Cursor, Claude Code, Codex, etc.) | Any tool supporting the Agent Skills open standard |
Run in your project directory to enable for that project:
cd /path/to/your/project
claude mcp add mcp-image --env GEMINI_API_KEY=your-api-key --env IMAGE_OUTPUT_DIR=/absolute/path/to/images -- npx -y mcp-image
Or add globally for all projects:
claude mcp add mcp-image --scope user --env GEMINI_API_KEY=your-api-key --env IMAGE_OUTPUT_DIR=/absolute/path/to/images -- npx -y mcp-image
⚠️ Security Note: Never commit your API key to version control. Keep it secure and use environment-specific configuration.
📁 Path Requirements:
IMAGE_OUTPUT_DIR must be an absolute path (e.g., /Users/username/images, not ./images)
Defaults to ./output in the current working directory if not specified
Directory will be created automatically if it doesn't exist
Quality Presets
Choose the right balance of speed, quality, and cost:
| Preset | Model | Best for | Speed |
|--------|-------|----------|-------|
| fast (default) | Nano Banana 2 (Gemini 3.1 Flash Image) | Quick iterations, drafts, high-volume generation | ~30–40s |
| balanced | Nano Banana 2 + Thinking | Production images, good quality with reasonable speed | Medium |
| quality | Nano Banana Pro (Gemini 3 Pro Image) | Final deliverables, maximum fidelity, critical visuals | Slow |
Set the default via IMAGE_QUALITY environment variable:
IMAGE_QUALITY=fast # (default) Fastest generation
IMAGE_QUALITY=balanced # Enhanced thinking for better quality
IMAGE_QUALITY=quality # Maximum quality output
To override per-request, just tell your AI assistant (e.g., "generate in high quality" or "use balanced quality"). The assistant will pass the appropriate quality parameter automatically.
Set SKIP_PROMPT_ENHANCEMENT=true to disable automatic prompt optimization and send your prompts directly to the image generator. Useful when you need full control over the exact prompt wording.
Usage Examples
Once configured, just describe what you want in natural language:
Basic Image Generation
"Generate a serene mountain landscape at sunset with a lake reflection"
Your prompt is automatically enhanced with rich details about lighting, materials, composition, and atmosphere.
Image Editing
"Edit this image to make the person face right"
(with inputImagePath: "/path/to/image.jpg")
Advanced Features
Character Consistency:
"Generate a portrait of a medieval knight, maintaining character consistency for future variations"
(with maintai
The agent harness performance optimization system. Skills, instincts, memory, security, and research-first development for Claude Code, Codex, Opencode, Cursor and beyond.
