Variable: UI_EXTENSION_ID

const UI_EXTENSION_ID: "io.modelcontextprotocol/ui" = 'io.modelcontextprotocol/ui'

Defined in: registerAppResource.ts:26

Identifier of the MCP Apps extension (io.modelcontextprotocol/ui), used as the key under capabilities.extensions on both sides of the handshake.

A client declares Apps support with it; a server may advertise the same key so a host can discover the support without inspecting tool metadata:

new McpServer(
  { name: 'weather', version: '1.0.0' },
  {
    capabilities: {
      extensions: {
        [UI_EXTENSION_ID]: { mimeTypes: [UI_RESOURCE_MIME_TYPE] },
      },
    },
  }
);