I’d like to see the Gemini Chat Node have better compatibility with MCPs, as they are more flexible and powerful than API calls.
When enabling MCPs, this is the error that comes up includes:
Unknown name “exclusiveMinimum”
Unknown name “exclusiveMaximum”
Unknown name “const”
Gemini models are stricter than OpenAI models — their schema validator only allows a narrower set (type, enum, minimum, maximum, items, properties, etc.), but not const or the “exclusive” variants.
When the Agent node builds the tool manifest to send to the model, Gemini sees those unsupported JSON Schema keywords and throws 400.
If I were to patch the n8n code directly, I would create a toggle in the Gemini Chat Node for “strip unsupported schemas”, which would take out keywords (exclusiveMinimum, exclusiveMaximum, const) from the tool schemas before they’re sent. Right now n8n doesn’t do this automatically.