mcp-server-openai-image-generator

An MCP (Model Context Protocol) server that exposes an OpenAI image generation tool over HTTP. It generates images from text prompts, saves them locally, and serves them via an integrated static file server.

Stack

• Runtime / Language: Bun + TypeScript
• MCP Transport: HTTP — standard JSON responses (POST /mcp)
• Image generation: OpenAI Images API (gpt-image-2 by default)
• CORS: Access-Control-Allow-Origin: * on all routes

Prerequisites

• Bun >= 1.0
• An OpenAI API key with access to the Images API

Installation

bun install

Configuration

Edit config.json at the project root:

{
  "port": 1980,
  "model": "gpt-image-2",
  "size": "1024x1536",
  "quality": "low",
  "imagesDir": "images"
}

Field	Description	Default
port	HTTP server listening port	1980
model	OpenAI image model	"gpt-image-2"
size	Generated image dimensions	"1024x1536"
quality	Image quality ("low", "medium", "high")	"low"
imagesDir	Directory where generated images are stored	"images"

The imagesDir directory is created automatically if it does not exist.

API Key

Provide your OpenAI key via the environment variable:

export OPENAI_API_KEY=sk-...

Usage

# production
bun run start

# development (watch mode)
bun run dev

The server starts on the configured port (default: http://localhost:1980).

MCP Tool: generate_image

Request

POST /mcp with a JSON-RPC 2.0 body:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "generate_image",
    "arguments": {
      "description": "A futuristic city at sunset, digital art"
    }
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "url": "http://localhost:1980/images/1720000000000.png",
    "filename": "1720000000000.png",
    "model": "gpt-image-2",
    "size": "1024x1536",
    "prompt": "A futuristic city at sunset, digital art"
  }
}

Generated images are saved as <timestamp>.png in imagesDir and immediately accessible at GET /images/:filename.

Project Structure

src/
  index.ts          # Entry point — loads config, starts server
  server.ts         # Bun HTTP server, routes requests
  mcpHandler.ts     # JSON-RPC 2.0 MCP handler
  imageGenerator.ts # OpenAI Images API integration
  staticHandler.ts  # Static file serving for generated images
  config.ts         # Config loading from config.json
  types.ts          # Shared TypeScript types
config.json         # Server configuration
images/             # Generated images (auto-created)

License

Private — all rights reserved.