How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/vercel-labs/json-render --skill mcpBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
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@json-render/mcp
MCP Apps integration that serves json-render UIs as interactive MCP Apps inside Claude, ChatGPT, Cursor, VS Code, and other MCP-capable clients.
Quick Start
Server (Node.js)
typescript
import { createMcpApp } from "@json-render/mcp";
import { defineCatalog } from "@json-render/core";
import { schema } from "@json-render/react/schema";
import { shadcnComponentDefinitions } from "@json-render/shadcn/catalog";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import fs from "node:fs";
const catalog = defineCatalog(schema, {
components: { ...shadcnComponentDefinitions },
actions: {},
});
const server = createMcpApp({
name: "My App",
version: "1.0.0",
catalog,
html: fs.readFileSync("dist/index.html", "utf-8"),
});
await server.connect(new StdioServerTransport());Client (React, inside iframe)
tsx
import { useJsonRenderApp } from "@json-render/mcp/app";
import { JSONUIProvider, Renderer } from "@json-render/react";
function McpAppView({ registry }) {
const { spec, loading, error } = useJsonRenderApp();
if (error) return <div>Error: {error.message}</div>;
if (!spec) return <div>Waiting...</div>;
return (
<JSONUIProvider registry={registry} initialState={spec.state ?? {}}>
<Renderer spec={spec} registry={registry} loading={loading} />
</JSONUIProvider>
);
}Architecture
createMcpApp()creates anMcpServerthat registers arender-uitool and aui://HTML resource- The tool description includes the catalog prompt so the LLM knows how to generate valid specs
- The HTML resource is a Vite-bundled single-file React app with json-render renderers
- Inside the iframe,
useJsonRenderApp()connects to the host viapostMessageand renders specs
Server API
createMcpApp(options)- main entry, creates a full MCP serverregisterJsonRenderTool(server, options)- register a json-render tool on an existing serverregisterJsonRenderResource(server, options)- register the UI resource
Client API (@json-render/mcp/app)
useJsonRenderApp(options?)- React hook, returns{ spec, loading, connected, error, callServerTool }buildAppHtml(options)- generate HTML from bundled JS/CSS
Building the iframe HTML
Bundle the React app into a single self-contained HTML file using Vite + vite-plugin-singlefile:
typescript
// vite.config.ts
import { defineConfig } from "vite";
import react from "@vitejs/plugin-react";
import { viteSingleFile } from "vite-plugin-singlefile";
export default defineConfig({
plugins: [react(), viteSingleFile()],
build: { outDir: "dist" },
});Client Configuration
Cursor (.cursor/mcp.json)
json
{
"mcpServers": {
"my-app": {
"command": "npx",
"args": ["tsx", "server.ts", "--stdio"]
}
}
}Claude Desktop
json
{
"mcpServers": {
"my-app": {
"command": "npx",
"args": ["tsx", "/path/to/server.ts", "--stdio"]
}
}
}Dependencies
bash
# Server
npm install @json-render/mcp @json-render/core @modelcontextprotocol/sdk
# Client (iframe)
npm install @json-render/react @json-render/shadcn react react-dom
# Build tools
npm install -D vite @vitejs/plugin-react vite-plugin-singlefile
