Documentation to use Flow as Tool

[sepa85]

I'm trying to use the experimental Flow as Tool component (class FlowToolComponent). I have the Flow A with an agent with tools, connected to the experimental Flow as Tool. This tool uses the Flow B, which have a text input and a text output.

With these configuration, I get the error: Error building Component Tool Calling Agent: 'message'

If I use chat input and chat output in Flow B, I get the same error: Error building Component Tool Calling Agent: 'message'

If I use the experimental "Message" component as Flow B output, I got no error, but the response from the tool is empty. I used Machine as sender type and tool as sender name.

How must I build the Flow used as tool? Which are the correct input and output component type? Is there documentation on Flow as Tool usage, maybe with examples?