— name: chatgpt-app-builder description: | DEPRECATED: This skill has been replaced by `mcp-app-builder`. Check if `mcp-app-builder` is available in the skills folder. If not, install it: `npx skills install mcp-use/mcp-use –skill mcp-app-builder` Use `mcp-app-builder` instead of this skill. Build ChatGPT apps with interactive widgets using mcp-use and OpenAI Apps SDK. Use when creating ChatGPT apps, building MCP servers with widgets, defining React widgets, working with Apps SDK, or when user mentions ChatGPT widgets, mcp-use widgets, or Apps SDK development. — # ChatGPT App Builder Build ChatGPT apps with interactive widgets using mcp-use. Zero-config widget development with automatic registration and built-in React hooks. The app is consumed by **two users at once**: the **human** and the **ChatGPT LLM**. They collaborate through the widget — the human interacts with it, the LLM sees its state. The widget is your shared surface. ## Before You Code – **Clarify what to build** → [discover.md](references/discover.md): when starting a new app, validating an idea, or scoping features – **Design tools and widgets** → [architecture.md](references/architecture.md): when deciding what needs UI vs tools-only, designing UX flows ## Setup – **Scaffold and run** → [setup.md](references/setup.md): when creating a new project, starting dev server, connecting to ChatGPT/Claude ## Implementation – **Server handlers + widget creation** → [server-and-widgets.md](references/server-and-widgets.md): when writing server.tool() with widgets, widget() helper, React widget files – **Widget state and LLM context** → [state-and-context.md](references/state-and-context.md): when persisting state, triggering LLM from widget, managing ephemeral vs persistent data – **Display modes, theme, layout** → [ui-guidelines.md](references/ui-guidelines.md): when adapting to inline/fullscreen/PiP, handling theme, device, locale – **Component API** → [components-api.md](references/components-api.md): when using McpUseProvider, Image, ErrorBoundary, useWidget – **CSP and metadata** → [csp-and-metadata.md](references/csp-and-metadata.md): when configuring external domains, dual-protocol metadata – **Advanced patterns** → [widget-patterns.md](references/widget-patterns.md): when building complex widgets with tool calls, state, theming ## Quick Reference “`typescript // Server import { MCPServer, widget, text, object } from "mcp-use/server"; server.tool({ name: "…", schema: z.object({…}), widget: { name: "widget-name" } }, async (input) => widget({ props: {…}, output: text("…") }) ); // Widget (resources/widget-name.tsx) import { McpUseProvider, useWidget, type WidgetMetadata } from "mcp-use/react"; export const widgetMetadata: WidgetMetadata = { description: "…", props: z.object({…}) }; export default function MyWidget() { const { props, isPending, callTool, sendFollowUpMessage, state, setState, theme } = useWidget(); if (isPending) return <McpUseProvider autoSize><div>Loading…</div></McpUseProvider>; return <McpUseProvider autoSize><div>{/* UI */}</div></McpUseProvider>; } “`