MCP CU Chat Server

A local MCP (Model Context Protocol) server that renders Azure Content Understanding (CU) field schema as an interactive table card directly inside VS Code Chat, using the MCP Apps extension (SEP-1865).

Features

• Renders CU field schema as a CU Studio–style table: Value Type / Method dropdowns, Source & Confidence checkbox, header info icons, truncated descriptions.
• Interactive: edit a field's description in the card; the edit is persisted back to the server (via callServerTool) and survives re-renders.
• Self-contained MCP App HTML bundle (esbuild), served over stdio.

Project structure

• server.mjs — MCP server: tool + UI resource registration, in-memory persistence.
• view/main.mjs — View logic: table rendering, editing, pulling latest from server.
• view/template.html — View HTML skeleton + styles.
• build.mjs — esbuild script that bundles the View into dist/mcp-app.html.
• data/sample-field-schema.json — sample CU field schema (13 fields).
• test-smoke.mjs — smoke test that verifies the MCP protocol without VS Code.

Setup

npm install
npm run build

Register in VS Code

Add to your user mcp.json (Command Palette → "MCP: Open User Configuration"):

{
  "servers": {
    "cu-schema-viewer": {
      "type": "stdio",
      "command": "node",
      "args": ["<absolute-path>/server.mjs"]
    }
  }
}

Restart the server (Command Palette → "MCP: List Servers" → cu-schema-viewer → Restart), then in Agent mode invoke the render_cu_schema tool.

Tools

• render_cu_schema — render the CU field schema table.
  • schemaPath (optional): absolute path to a JSON file with fieldSchema.fields.
  • fieldSchema (optional): inline fieldSchema object.
• update_field_description (UI-only) — persists an edited field description.

Gotcha: MCP Apps ui:// authority must equal the server name

VS Code routes UI resource requests by the authority segment of the ui:// URI. It must equal the server name in mcp.json, otherwise VS Code never sends resources/read and the card won't render (you only get text output). This server uses ui://cu-schema-viewer/schema to match the server name cu-schema-viewer.