gemini-image-mcp

MCP server for Google Gemini image generation, editing, and processing. Two tools, no bloat.

Built on Gemini's native image generation API (generateContent), not the deprecated Imagen API. If you're migrating from Imagen (shutting down June 2026), this is what you move to — multi-turn editing, reference images, and all the features Imagen didn't have.

Install

npm install -g @jimothy-snicket/gemini-image-mcp

Or use directly with npx:

npx -y @jimothy-snicket/gemini-image-mcp

Claude Code (one command):

claude mcp add gemini-image -- npx -y @jimothy-snicket/gemini-image-mcp

Requires a GEMINI_API_KEY environment variable — see Setup for details.

Set up a config file (optional):

npx @jimothy-snicket/gemini-image-mcp --init

Creates ~/.gemini-image-mcp.json with commented defaults. For project-specific overrides:

npx @jimothy-snicket/gemini-image-mcp --init --local

Features

generate_image — AI-powered

• Text-to-image — describe what you want, get an image
• Image editing — provide reference images and an editing instruction
• Multi-turn sessions — iteratively refine images with conversation history
• Multi-image input — up to 14 reference images on gemini-3-pro
• Cost reporting — every response includes token counts, estimated USD cost, and session totals
• Rate limiting — configurable per-hour caps on requests and cost to prevent runaway agents
• Auto model discovery — detects available image models from your API key at startup
• Seed — reproducible generation with integer seeds
• Google Search grounding — real-world accuracy on gemini-3.1-flash

process_image — Local (free, no API calls)

• Crop — pixel-exact, aspect ratio (center), or focal point (attention/entropy)
• Resize — to width, height, or both (maintains aspect ratio)
• Background removal — threshold-based (white backgrounds) or chroma key (green screen, any solid colour)
• Chroma key pipeline — HSV keying with smoothstep feather, spill suppression, and edge anti-aliasing
• Trim — auto-remove whitespace borders
• Format conversion — PNG, JPEG, WebP with quality control

Both tools

• Output organization — meaningful filenames with auto-versioning, subfolders
• Generation manifest — generations.jsonl logs every generation with prompt, params, cost
• Full aspect ratio support — 1:1, 16:9, 9:16, 3:2, 2:3, 4:3, 3:4, 21:9
• Resolution control — 1K, 2K, 4K

Setup

1. Get a Gemini API Key

Go to Google AI Studio and create an API key. It's free to start with generous rate limits.

2. Set the API Key

The server reads your key from the GEMINI_API_KEY environment variable. Set it once so it's available in every session:

Windows (PowerShell — run as admin):

[System.Environment]::SetEnvironmentVariable('GEMINI_API_KEY', 'your-key-here', 'User')

Then restart your terminal.

macOS / Linux:

echo 'export GEMINI_API_KEY="your-key-here"' >> ~/.bashrc
source ~/.bashrc

(Use ~/.zshrc if you're on zsh.)

Verify it's set:

echo $GEMINI_API_KEY

3. Connect to Your MCP Client

Pick the method that matches how you use MCP:

Claude Code (one-liner)

claude mcp add gemini-image -- npx -y @jimothy-snicket/gemini-image-mcp

Claude Code will pick up GEMINI_API_KEY from your environment automatically.

Claude Code (manual .mcp.json)

Add to .mcp.json in your project root or ~/.claude/.mcp.json for global access:

{
  "mcpServers": {
    "gemini-image": {
      "command": "npx",
      "args": ["-y", "@jimothy-snicket/gemini-image-mcp"],
      "env": {
        "GEMINI_API_KEY": "${GEMINI_API_KEY}"
      }
    }
  }
}

The ${GEMINI_API_KEY} syntax reads the value from your shell environment — your actual key never gets written into config files.

Claude Desktop

Edit claude_desktop_config.json:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "gemini-image": {
      "command": "npx",
      "args": ["-y", "@jimothy-snicket/gemini-image-mcp"],
      "env": {
        "GEMINI_API_KEY": "${GEMINI_API_KEY}"
      }
    }
  }
}

Restart Claude Desktop after saving.

Other MCP Clients

Any client that supports stdio transport works. Point it at npx -y @jimothy-snicket/gemini-image-mcp and pass GEMINI_API_KEY in the environment.

Security Notes

• Never commit your API key to version control. The ${GEMINI_API_KEY} syntax in config files references your environment — the key itself stays in your shell profile.
• If your .mcp.json is in a project repo, add it to .gitignore or use the global config at ~/.claude/.mcp.json instead.
• For extra security, you can use a wrapper script that reads the key from your OS keychain (macOS Keychain, Windows Credential Manager) and launches the server with it injected.

Configuration

All optional. The only required setup is GEMINI_API_KEY (covered above).

| Variable | Default | Description | |----------|---------|-------------| | OUTPUT_DIR | ~/gemini-images | Default directory for saved images | | DEFAULT_MODEL | gemini-2.5-flash-image | Default Gemini model | | LOG_LEVEL | info | debug, info, or error | | REQUEST_TIMEOUT_MS | 60000 | API request timeout in milliseconds | | MAX_REQUESTS_PER_HOUR | 0 (unlimited) | Max image generations per rolling hour | | MAX_COST_PER_HOUR | 0 (unlimited) | Max estimated cost (USD) per rolling hour | | SESSION_TIMEOUT_MS | 1800000 (30min) | Multi-turn session expiry |

Set these the same way as GEMINI_API_KEY, or pass them in the env block of your MCP config.

Rate limiting is recommended when agents have access to this tool. An agent in a loop can generate images quickly — set MAX_REQUESTS_PER_HOUR=20 and MAX_COST_PER_HOUR=5 as sensible defaults.

Config File

Instead of environment variables, you can use a JSON config file. Create one with:

npx @jimothy-snicket/gemini-image-mcp --init

This creates ~/.gemini-image-mcp.json with all defaults and inline documentation. Edit it to set your preferences.

Priority: env vars > local config (.gemini-image-mcp.json in CWD) > global config (~/.gemini-image-mcp.json) > defaults.

You can also set per-tool defaults so every request uses your preferred settings:

{
  "defaultModel": "gemini-3.1-flash-image-preview",
  "defaults": {
    "generate": {
      "aspectRatio": "16:9",
      "resolution": "2K"
    },
    "process": {
      "removeBackground": { "color": "#00FF00" },
      "trim": true
    }
  }
}

Per-request parameters always override config defaults.

Tool: generate_image

Parameters

| Parameter | Required | Description | |-----------|----------|-------------| | prompt | Yes | Text description or editing instruction | | images | No | Array of file paths to input/reference images | | model | No | Gemini model ID | | aspectRatio | No | 1:1, 16:9, 9:16, 3:2, 2:3, 4:3, 3:4, 21:9 | | resolution | No | 1K, 2K, 4K | | outputDir | No | Override output directory for this request | | filename | No | Base name for saved file (e.g. hero-banner). Auto-versioned if duplicate. | | subfolder | No | Subfolder within output directory (e.g. landing-page) | | sessionId | No | Continue a multi-turn editing session from a previous response | | seed | No | Integer seed for reproducible generation | | useSearchGrounding | No | Enable Google Search grounding (gemini-3.1-flash) |

Example Response

{
  "imagePath": "/home/user/gemini-images/hero-banner.png",
  "mimeType": "image/png",
  "model": "gemini-2.5-flash-image",
  "sessionId": "session-1711929600000-a1b2c3",
  "sessionTurn": 1,
  "usage": {
    "promptTokens": 5,
    "outputTokens": 1295,
    "imageTokens": 1290,
    "thinkingTokens": 412,
    "totalTokens": 1712,
    "estimatedCost": "$0.0390"
  },
  "session": {
    "generationsThisSession": 3,
    "totalCostThisSession": "$0.1161",
    "generationsThisHour": 5,
    "limit": {
      "maxPerHour": 20,
      "maxCostPerHour": 5,
      "remainingThisHour": 15
    }
  }
}

Usage Examples

Text-to-image:

"Generate a hero image for a SaaS landing page, modern gradient style, 16:9"

Image editing:

"Take this screenshot and redesign the header with a dark theme" (with image paths)

Multi-turn refinement:

"Draw a logo for a coffee shop" → get result with sessionId → "Make it more minimal" (pass sessionId back)

Organized output:

"Generate a hero banner" with filename: "hero", subfolder: "landing-page" → saves to ~/gemini-images/landing-page/hero.png

High quality:

"A photorealistic product shot of headphones on marble, 4K" (using gemini-3-pro-image-preview)

Tool: process_image

Local image processing via sharp. Free, fast, no API calls.

Parameters

| Parameter | Required | Description | |-----------|----------|-------------| | imagePath | Yes | Path to the image file to process | | crop | No | Crop by pixel dimensions, aspect ratio, or focal point strategy | | resize | No | Resize to width/height (maintains aspect ratio) | | removeBackground | No | Remove background by threshold (white) or chroma key (any solid colour) | | trim | No | Auto-remove whitespace/transparent borders | | format | No | Convert to png, jpeg, or webp | | quality | No | Output quality for JPEG/WebP (1-100) | | filename | No | Base name for saved file. Auto-versioned if duplicate. | | subfolder | No | Subfolder within output directory | | outputDir | No | Override output directory |

Crop Options

// Pixel-exact
{"width": 500, "height": 300, "left": 100, "top": 50}

// Aspect ratio (center crop)
{"aspectRatio": "16:9"}

// Focal point — shifts crop to the most interesting region
{"aspectRatio": "16:9", "strategy": "attention"}

// Detail-based — shifts crop to the most detailed region
{"aspectRatio": "16:9", "strategy": "entropy"}

Background Removal Options

// White/light background (threshold)
{"threshold": 240}

// Green screen (chroma key)
{"color": "#00FF00"}

// Any solid colour
{"color": "#0000FF", "tolerance": 60}

Chroma key uses HSV colour space keying with smoothstep feathering, spill suppression (removes colour fringe on edge pixels), and 5-pass edge anti-aliasing. Default tolerance is 80. Always use #00FF00 for AI-generated green screens — it works better than matching the exact shade Gemini produces.

Note: Chroma key works best with high-contrast subjects (red, blue, black on green). For yellow, green, or glass/reflective subjects, use the canvas approach instead — feed a solid colour background image to generate_image and let Gemini place the subject with correct lighting.

Common Pipelines

Subject on a specific background (canvas approach):

generate_image → "Place a [subject] on this background" with images: [solid colour canvas]

One API call. Best for yellow, green, or glass subjects where chroma key struggles.

Transparent asset from green screen:

generate_image → "A product photo on a bright green background"
process_image → removeBackground {color: "#00FF00"} + trim

Two tool calls, zero cost for the processing step. Best for high-contrast subjects.

Favicon from a generated logo:

process_image → removeBackground {threshold: 230} + trim + resize {width: 192, height: 192}

Social card from a photo:

process_image → crop {aspectRatio: "16:9", strategy: "attention"} + resize {width: 1200}

WebP conversion for web:

process_image → format: "webp" + quality: 85

Models

| Model | Strengths | Resolution | Notes | |-------|-----------|------------|-------| | gemini-2.5-flash-image | Fast, cheap (~$0.04/image) | 1K only | Default. Deprecates Oct 2026 | | gemini-3-pro-image-preview | Best quality, text rendering | 1K, 2K, 4K | Up to 14 reference images | | gemini-3.1-flash-image-preview | Speed + quality balance | 512, 1K, 2K, 4K | Google Search grounding |

Development

bun install
bun run build     # TypeScript -> dist/
bun run dev       # Run directly with Bun

License

MIT