Render interactive MCP Apps
Some answers are not sentences. Choosing between twelve flights, filling in a booking form, picking a date - these are worse as text than as an interface, no matter how well the model writes.
An MCP tool can return an app resource, and AXL renders it in the web client. The app runs in a distinct-origin sandbox and can call approved host tools back through the app-to-host bridge, so what the user clicks turns into real actions in the run.
To use one:
- Connect the MCP server in the agent's
mcp.toml. - Make the app-producing tool available to the agent.
- Call the tool from a web chat session.
- Interact with the rendered result in the client.
What this is and is not
Interactive apps are delivered by the tool. AXL does not convert ordinary HTML in a response into an app, and an agent cannot decide to render an interface on its own - the MCP server has to produce the app resource. That constraint is deliberate: it keeps arbitrary model output from becoming executable UI.
Authentication and authorization still follow the MCP server's configuration and the user's session. The sandbox limits what the app can reach, not who the user is.
Next
- Connect an MCP server - the configuration that makes the tool available.
- - transports and authentication.
- - how the sandbox and bridge work.