Gemini MCP Server

An MCP (Model Context Protocol) server that provides access to Google's Gemini API. Drop-in alternative to Codex MCP with matching interface.

Features

• gemini - Start a new Gemini conversation with configurable context
• gemini-reply - Continue multi-turn conversations
• gemini-image - Generate images using Nano Banana (Gemini's native image generation)

Installation

npm install
npm run build

Configuration

Create a .env file or set environment variables:

# Required: Your Google Gemini API key
GEMINI_API_KEY=your_api_key_here

# Optional: Override the model (default: gemini-3-pro-preview)
GEMINI_MODEL=gemini-3-pro-preview

Get your API key from Google AI Studio.

Usage with Claude Code

Add to your MCP settings (~/.claude/mcp.json):

{
  "mcpServers": {
    "gemini": {
      "command": "node",
      "args": ["/path/to/gemini-mcp/dist/index.js"],
      "env": {
        "GEMINI_API_KEY": "your_api_key_here"
      }
    }
  }
}

Tools

gemini

Start a new conversation with Gemini.

Parameters:

• prompt (required) - The initial prompt
• cwd - Working directory context
• sandbox - Access policy: "read-only", "workspace-write", or "danger-full-access"
• base-instructions - Override default system instructions
• developer-instructions - Additional context for the model

Returns: Response text and a conversationId for follow-up.

gemini-reply

Continue an existing conversation.

Parameters:

• conversationId (required) - ID from a previous gemini call
• prompt (required) - Your follow-up message

gemini-image

Generate images using Nano Banana, Google's native image generation built into Gemini.

Models:

• Nano Banana (gemini-2.5-flash-image) - Fast, cost-effective (~$0.04/image), good for most use cases
• Nano Banana Pro (gemini-3-pro-image-preview) - Advanced model with better text rendering, ideal for infographics, diagrams, and text-heavy images

Auto-Detection: The server automatically uses Nano Banana Pro when your prompt contains keywords like:

• "nano banana pro", "pro model"
• "infographic", "diagram", "chart", "graph"
• "text", "typography", "font", "lettering"
• "logo", "brand", "poster", "flyer", "banner"
• "slide", "presentation", "document"
• "high quality", "4k", "detailed text"

Parameters:

• prompt (required) - Description of the image to generate
• numberOfImages - How many images (1-4, default: 1)
• aspectRatio - Image ratio: "1:1", "3:4", "4:3", "9:16", "16:9"
• usePro - Force Nano Banana Pro (auto-detected from prompt if not specified)
• outputPath - Directory to save generated images

Example:

// Auto-detects Pro model
"Create an infographic showing the software development lifecycle"

// Explicitly request Pro
{ "prompt": "A sunset over mountains", "usePro": true }

// Fast generation (default)
"A cute cat wearing a hat"

Development

# Run in development mode
npm run dev

# Build for production
npm run build

# Start production server
npm start

License

MIT