Issue with using Google models when an agent has tools

[kyen99]

This Helicone n8n node is such a great idea! Thanks for putting this together.

This worked perfectly for a basic AI agent using claude-sonnet-4/bedrock. However, when I tried to use gemini-3-flash-preview/vertex with the exact same agent I got errors that Google's API didn't like the $schema key provided as part of the tool descriptions. As soon as I change the model back to Claude it works. If I use a Google model but I remove the tools from the agent, it also works. I'm using BYOK in both cases.

With a simple agent with one tool (all with BYOK)...

This worked:
claude-sonnet-4/bedrock

This didn't work:
gemini-3-flash-preview/vertex
gemini-3-flash-preview/google-ai-studio

Here is one of the errors from Helicone...

{ "error": { "code": 400, "message": "Invalid JSON payload received. Unknown name \"$schema\" at 'tools[0].function_declarations[0].parameters': Cannot find field.\nInvalid JSON payload received. Unknown name \"$schema\" at 'tools[0].function_declarations[1].parameters': Cannot find field.", "status": "INVALID_ARGUMENT", "details": [ { "@type": "type.googleapis.com/google.rpc.BadRequest", "fieldViolations": [ { "field": "tools[0].function_declarations[0].parameters", "description": "Invalid JSON payload received. Unknown name \"$schema\" at 'tools[0].function_declarations[0].parameters': Cannot find field." }, { "field": "tools[0].function_declarations[1].parameters", "description": "Invalid JSON payload received. Unknown name \"$schema\" at 'tools[0].function_declarations[1].parameters': Cannot find field." } ] } ] } }

I'm happy to provide more information if that would help.