Awesome-omni-skill mcpserver

Migrates an MCP server with interactive widgets from the OpenAI Apps SDK (window.openai, text/html+skybridge) to the MCP Apps standard (@modelcontextprotocol/ext-apps), covering server-side and client-side changes.

install

source · Clone the upstream repo

git clone https://github.com/diegosouzapw/awesome-omni-skill

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/diegosouzapw/awesome-omni-skill "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/backend/mcpserver" ~/.claude/skills/diegosouzapw-awesome-omni-skill-mcpserver && rm -rf "$T"

manifest: skills/backend/mcpserver/SKILL.md

source content

Skill: Migrate OpenAI Apps SDK → MCP Apps

Migrate an MCP server with interactive widgets from the OpenAI Apps SDK (

window.openai

text/html+skybridge

, flat

_meta["openai/..."]

keys) to the MCP Apps standard (

@modelcontextprotocol/ext-apps

When to Use

Use this skill when:

An MCP server uses
```
text/html+skybridge
```
MIME type for widget resources

Widget code references

window.openai

globals (e.g.

window.openai.callTool

window.openai.toolOutput

window.openai.theme

)

Server code uses flat

_meta["openai/outputTemplate"]

_meta["openai/widgetAccessible"]

keys

The goal is to make the server compatible with MCP Apps hosts (Claude, ChatGPT, Microsoft 365 Copilot, etc.)

References

MCP Apps repo: https://github.com/modelcontextprotocol/ext-apps
API docs: https://modelcontextprotocol.github.io/ext-apps/api/
Migration guide: https://modelcontextprotocol.github.io/ext-apps/docs/migration/openai-apps
Patterns: https://modelcontextprotocol.github.io/ext-apps/docs/patterns

Packages

Package	Where	Purpose
`@modelcontextprotocol/ext-apps`	Server + Widgets	Core MCP Apps SDK
`@modelcontextprotocol/sdk`	Server	MCP protocol SDK (keep existing)
`zod`	Server	Schema definitions for `McpServer.tool()`

Migration Mapping

MIME Type

Before After

text/html+skybridge

text/html;profile=mcp-app

(use

RESOURCE_MIME_TYPE

constant)

Server:

_meta

Keys

OpenAI flat key	MCP Apps nested key
`_meta["openai/outputTemplate"]` (URI string)	`_meta.ui.resourceUri` (URI string)
`_meta["openai/widgetAccessible"]: true`	`_meta.ui.visibility: ["widget"]`

Server: Class & Helpers

Before	After
`import { Server } from "@modelcontextprotocol/sdk/server/index.js"`	`import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js"`
`new Server({ name, version }, { capabilities })`	`new McpServer({ name, version })`
`server.setRequestHandler(ListToolsRequestSchema, ...)`	`server.tool(name, desc, schema, handler)` or `registerAppTool(...)`
`server.setRequestHandler(ReadResourceRequestSchema, ...)`	`registerAppResource(...)`
Manual tool/resource list handlers	Automatic via `McpServer` + helpers

Server: Tool Registration

Widget tools (tools that render UI) use

registerAppTool

import { registerAppTool, registerAppResource, RESOURCE_MIME_TYPE } from "@modelcontextprotocol/ext-apps/server";
import { z } from "zod";

const WIDGET_URI = "ui://myapp/widget.html";

registerAppResource(server, "Widget Name", WIDGET_URI, {
  mimeType: RESOURCE_MIME_TYPE,
  description: "Description of the widget",
}, async (): Promise<ReadResourceResult> => {
  const html = await fs.readFile(widgetPath, "utf-8");
  return { contents: [{ uri: WIDGET_URI, mimeType: RESOURCE_MIME_TYPE, text: html }] };
});

registerAppTool(server, "show-widget", {
  title: "Show Widget",
  description: "Displays the widget",
  inputSchema: {
    filter: z.string().optional().describe("Optional filter"),
  },
  annotations: { readOnlyHint: true },
  _meta: { ui: { resourceUri: WIDGET_URI } },
}, async ({ filter }): Promise<CallToolResult> => {
  const data = await fetchData(filter);
  return {
    content: [{ type: "text", text: `Loaded ${data.length} items.` }],
    structuredContent: { items: data },
  };
});

Data-only tools (no UI) use

server.tool()

directly:

server.tool("update-item", "Updates an item.", {
  id: z.string().describe("Item ID"),
  status: z.string().describe("New status"),
}, async ({ id, status }) => {
  await db.update(id, { status });
  return { content: [{ type: "text" as const, text: `Updated ${id}.` }] };
});

Client (Widget): Global API

OpenAI ( `window.openai` )	MCP Apps ( `App` from `@modelcontextprotocol/ext-apps` )
`window.openai.toolOutput`	`app.ontoolresult = (result) => result.structuredContent`
`window.openai.callTool(name, args)`	`app.callServerTool({ name, arguments: args })`
`window.openai.theme` ( `"light"` / `"dark"` )	`app.getHostContext()?.theme` ( `"light"` / `"dark"` )
`window.openai.displayMode`	`app.getHostContext()?.displayMode`
`window.openai.requestDisplayMode(mode)`	`app.requestDisplayMode(mode)`
`window.addEventListener("openai:set_globals", ...)`	`app.onhostcontextchanged = (ctx) => { ... }`
N/A	`app.onteardown = () => { ... }`

Client (Widget): React Hook

Before After

useOpenAiGlobal("toolOutput")

useMcpToolData<T>()

(custom hook wrapping

useApp

)

useOpenAiGlobal("theme")

useMcpTheme()

(custom hook returning

"light"

"dark"

)

Step-by-Step Migration Process

1. Update Dependencies

Server

package.json

— add:

"@modelcontextprotocol/ext-apps": "^1.0.0",
"zod": "^3.25.0"

Widgets

package.json

— add:

"@modelcontextprotocol/ext-apps": "^1.0.0"

2. Create MCP Apps React Context (Widgets)

Create a shared hook file (e.g.

hooks/useMcpApp.tsx

) that wraps the

App

class:

import React, { createContext, useContext, useEffect, useState, useRef } from "react";
import { useApp } from "@modelcontextprotocol/ext-apps/react";

interface McpAppContextValue {
  app: ReturnType<typeof useApp>;
  toolData: unknown;
  theme: "light" | "dark";
  hostContext: { theme?: string; displayMode?: string } | null;
}

const McpAppContext = createContext<McpAppContextValue | null>(null);

export function McpAppProvider({ name, children }: { name: string; children: React.ReactNode }) {
  const app = useApp({ name });
  const [toolData, setToolData] = useState<unknown>(null);
  const [theme, setTheme] = useState<"light" | "dark">("light");
  const [hostContext, setHostContext] = useState<{ theme?: string; displayMode?: string } | null>(null);

  useEffect(() => {
    app.ontoolresult = (result: any) => {
      if (result?.structuredContent) setToolData(result.structuredContent);
    };
    app.onhostcontextchanged = (ctx: any) => {
      setHostContext(ctx);
      if (ctx?.theme === "dark" || ctx?.theme === "light") setTheme(ctx.theme);
    };
    const initial = app.getHostContext?.();
    if (initial) {
      setHostContext(initial);
      if (initial.theme === "dark" || initial.theme === "light") setTheme(initial.theme);
    }
  }, [app]);

  return (
    <McpAppContext.Provider value={{ app, toolData, theme, hostContext }}>
      {children}
    </McpAppContext.Provider>
  );
}

export function useMcpApp() {
  const ctx = useContext(McpAppContext);
  if (!ctx) throw new Error("useMcpApp must be used within McpAppProvider");
  return ctx;
}

export function useMcpToolData<T = unknown>(): T | null {
  const { toolData } = useMcpApp();
  return toolData as T | null;
}

export function useMcpTheme(): "light" | "dark" {
  const { toolData, theme } = useMcpApp();
  return theme;
}

3. Update Widget Entry Points (

main.tsx

)

Wrap the app in

<McpAppProvider>

instead of reading

window.openai

import { McpAppProvider, useMcpTheme } from "../hooks/useMcpApp";

function ThemedApp() {
  const theme = useMcpTheme();
  return (
    <FluentProvider theme={theme === "dark" ? webDarkTheme : webLightTheme}>
      <MyWidget />
    </FluentProvider>
  );
}

createRoot(document.getElementById("root")!).render(
  <McpAppProvider name="My Widget">
    <ThemedApp />
  </McpAppProvider>
);

4. Update Widget Components

Replace all

window.openai

references:

// BEFORE
const toolOutput = useOpenAiGlobal("toolOutput");
window.openai.callTool("update-item", { id: "1", status: "done" });
window.openai.requestDisplayMode(
  window.openai.displayMode === "expanded" ? "default" : "expanded"
);

// AFTER
const toolData = useMcpToolData<MyDataType>();
const { app, hostContext } = useMcpApp();
app.callServerTool({ name: "update-item", arguments: { id: "1", status: "done" } });
app.requestDisplayMode(
  hostContext?.displayMode === "expanded" ? "default" : "expanded"
);

5. Rewrite Server (

mcp-server.ts

)

Replace
```
Server
```
with
```
McpServer
```

Replace manual

setRequestHandler

with

registerAppTool

registerAppResource

server.tool()

Use
```
RESOURCE_MIME_TYPE
```
instead of
```
"text/html+skybridge"
```
Use
```
zod
```
schemas for tool input definitions
Return
```
structuredContent
```
(object) alongside
```
content
```
(text array) from widget tools

6. Update Server Entry Point (

index.ts

)

Switch from

server.connect(transport)

with a low-level

Server

McpServer

import { createMcpServer } from "./mcp-server.js";

app.all("/mcp", async (req, res) => {
  const server = createMcpServer(); // returns McpServer
  const transport = new StreamableHTTPServerTransport({
    sessionIdGenerator: undefined,
    enableJsonResponse: true,
  });
  await server.connect(transport);
  await transport.handleRequest(req, res, req.body);
});

7. Build & Test

npm run install:all
npm run build:widgets
npm run dev:server

Verify with the MCP Inspector (

npx @modelcontextprotocol/inspector

) or connect from a host like Claude.

Common Pitfalls

Issue	Fix
`window.openai is undefined`	You missed replacing a `window.openai` reference in a widget component
Widget shows but no data	Ensure `structuredContent` is returned from the tool handler (not just `content` )
Theme not updating	Wire up `app.onhostcontextchanged` and call `setTheme()`
`registerAppTool` type errors	Import from `@modelcontextprotocol/ext-apps/server` , use `zod` for `inputSchema`
SSE gateway errors	Set `enableJsonResponse: true` on `StreamableHTTPServerTransport`
Resource not found by host	Ensure the `resourceUri` in `_meta.ui` exactly matches the URI in `registerAppResource`

Files Typically Changed

File	Change
`server/package.json`	Add `@modelcontextprotocol/ext-apps` , `zod`
`widgets/package.json`	Add `@modelcontextprotocol/ext-apps`
`server/src/mcp-server.ts`	Full rewrite: `McpServer` + `registerAppTool` + `registerAppResource`
`server/src/index.ts`	Update imports, `createMcpServer()` now returns `McpServer`
`widgets/src/hooks/useMcpApp.tsx`	New file: MCP Apps React context
`widgets/src/hooks/useThemeColors.ts`	Update import to use `useMcpTheme`
`widgets/src/**/main.tsx`	Wrap in `McpAppProvider` , use `useMcpTheme`
`widgets/src/*/.tsx`	Replace all `window.openai.*` calls
`widgets/src/hooks/useOpenAiGlobal.ts`	Can be deleted after migration

Awesome-omni-skill mcpserver

Skill: Migrate OpenAI Apps SDK → MCP Apps

When to Use

References

Packages

Migration Mapping

MIME Type

Server:
`_meta`
Keys

Server: Class & Helpers

Server: Tool Registration

Client (Widget): Global API

Client (Widget): React Hook

Step-by-Step Migration Process

1. Update Dependencies

2. Create MCP Apps React Context (Widgets)

3. Update Widget Entry Points (
`main.tsx`
)

4. Update Widget Components

5. Rewrite Server (
`mcp-server.ts`
)

6. Update Server Entry Point (
`index.ts`
)

7. Build & Test

Common Pitfalls

Files Typically Changed

Awesome-omni-skill mcpserver

Skill: Migrate OpenAI Apps SDK → MCP Apps

When to Use

References

Packages

Migration Mapping

MIME Type

Server: _meta Keys

Server: Class & Helpers

Server: Tool Registration

Client (Widget): Global API

Client (Widget): React Hook

Step-by-Step Migration Process

1. Update Dependencies

2. Create MCP Apps React Context (Widgets)

3. Update Widget Entry Points (main.tsx)

4. Update Widget Components

5. Rewrite Server (mcp-server.ts)

6. Update Server Entry Point (index.ts)

7. Build & Test

Common Pitfalls

Files Typically Changed

Server:
`_meta`
Keys

3. Update Widget Entry Points (
`main.tsx`
)

5. Rewrite Server (
`mcp-server.ts`
)

6. Update Server Entry Point (
`index.ts`
)