AI Agent with Google Firestore as a tool - can't make it work

I am having difficulties to make AI Agent work with Google Cloud Firestore Tool (Create or update document version).
I am unable to establish a proper fields mapping to collection/sub-collection, document, field, value.
The output of AI Agent is a huge JSON document, the fields the tool requires are:

  • Collection - that is easy
  • Update Key - no idea how it works, it is supposed to be the name of the document but it is totally ignored
  • Columns/Attributes - they are supposed to be the names of the fields to read from the input so n8n will take their values and save/update them

It doesn’t work if I drag and drop the field, it also doesn’t work if I try to provide the path to the field.

After many hours I couldn’t make it work at all. There is a lack of documentation and examples, or at least I failed to find them.

Can someone please explain how it works and hopefully share the workflow?

My workflow is simple:
Chat Trigger → AI Agent + Anthropic Sonnet → Firestore tool
And I expect it to create/update document

I made a similar one by HTTP tools, please take a try. I tried to submit as template but got rejected.