build-mcp-app

To add interactive UI widgets to an MCP server, you register UI metadata on tools using a _meta.ui.resourceUri, serve the corresponding HTML resource with the correct apps MIME type, and use the ext-apps runtime to handle ontoolresult events and user actions.

Yes, you can render interactive forms and dashboards inline with MCP tool results by building widget-enabled MCP apps that serve separate UI resources, which the chat host renders as interactive iframes within the conversation.

The ext-apps App runtime provides a host-aware sandbox connection pattern that allows widget code to receive tool results, send user-driven messages back into the conversation, and comply with CSP and iframe sandbox constraints.

Yes, the build-mcp-app approach supports two deployment shapes: building remote MCP app servers that serve UI resources over HTTP, and packaging local MCPB apps that bundle the UI layer directly within the deployment.

You should add UI components to an MCP server deployment when you need interactive app surfaces like picker or table style selections, confirmation dialogs for destructive actions, inline visual output displays, or progress-style status widgets.

To send a user's widget selection back into the MCP conversation, you use the ext-apps App runtime to handle user actions and send user-driven messages from the rendered iframe directly into the host chat experience.