Subnode of Sheets doesn't work in AI Agent

Hi everyone,
I’m using n8n version 1.91.2 locally on Windows. I’m trying to use the AI Agent with Google Sheets as a tool. I connected the sheet to the Tool port and set the tool description manually. However, the AI Agent never calls the tool, and I always get this message:

“None of your tools were used in this run. Try giving your tools clearer names and descriptions to help the AI.”

The Tool Name field does not appear in the Google Sheets node, even though I created a .env file with FEATURE_FLAG_AI_FUNCTION_TOOLS=true, and I also tried launching n8n with a .bat file that sets the variable. Still, the tool is never used.

What am I missing? How do I get the AI Agent to actually call the tool and use the content from Google Sheets?

Thanks!

It is hard to say without looking at the workflow, would you like to share your workflow?