openai-apps-mcp

# Building OpenAI Apps with Stateless MCP Servers **Status**: Production Ready **Last Updated**: 2026-01-21 **Dependencies**: `cloudflare-worker-base`, `hono-routing` (optional) **Latest Versions**: @modelcontextprotocol/sdk@1.25.3, hono@4.11.3, zod@4.3.5, wrangler@4.58.0 --- ## Overview Build **ChatGPT Apps** using **MCP (Model Context Protocol)** servers on Cloudflare Workers. Extends ChatGPT with custom tools and interactive widgets (HTML/JS UI rendered in iframe). **Architecture**: ChatGPT → MCP endpoint (JSON-RPC 2.0) → Tool handlers → Widget resources (HTML) **Status**: Apps available to Business/Enterprise/Edu (GA Nov 13, 2025). MCP Apps Extension (SEP-1865) formalized Nov 21, 2025. --- ## Quick Start ### 1. Scaffold & Install ```bash npm create cloudflare@latest my-openai-app -- --type hello-world --ts --git --deploy false cd my-openai-app npm install @modelcontextprotocol/sdk@1.25.3 hono@4.11.3 zod@4.3.5 npm install -D @cloudflare/vite-plugin@1.17.1 vite@7.2.4 ``` ### 2. Configure wrangler.jsonc ```jsonc { "name": "my-openai-app", "main": "dist/index.js", "compatibility_flags": ["nodejs_compat"], // Required for MCP SDK "assets": { "directory": "dist/client", "binding": "ASSETS" // Must match TypeScript } } ``` ### 3. Create MCP Server (`src/index.ts`) ```typescript import { Hono } from 'hono'; import { cors } from 'hono/cors'; import { Server } from '@modelcontextprotocol/sdk/server/index.js'; import { ListToolsRequestSchema, CallTo...