Claude fails to invoke/render MCP App ui element for tool call.

### What happened?

We've implemented a MCP App based ui element for one of our Tools on the Teamwork.com MCP server.
https://github.com/Teamwork/mcp
4

Testing in the MCP Inspector, the "App" is listed and correctly renders and functions correctly.
https://github.com/Teamwork/mcp/pull/156/changes#diff-08f191af8e1e82a6a13003714422dcc5f7064a2ba50f2fd0aab6e4fa1e19abeb

The UI element fails to render in Claude Desktop. Claude Desktop recognizes it as interactive, but Claude Desktop 1.1.2998 returns plain text only

What are we missing ?

### What did you expect to happen?

Claude to render the UI Form based on the metadata
```
Meta: mcp.Meta{
"ui": map[string]any{
"resourceUri": timelogCreateAppResourceURI,
},
},
```

### Steps to reproduce

Connect to Teamwork.com MCP Server
https://github.com/Teamwork/mcp/blob/main/usage.md

Create Timelog -> invoke projects-create_timelog tool call.

### Area

Tool Discovery / Invocation

### MCP Server (if applicable)

Teamwork.com (Streamable HTTP)

### Error messages or logs

```shell
None, just no UI invocation
```

### Additional context

_No response_