Gemini API returns 400 Invalid JSON payload when using Claude Code due to strict JSON Schema fields

When using Claude Code routed through llmgateway to a Gemini 3.1 Pro backend (google-ai-studio), the request fails with a 400 error. The error occurs because Claude Code sends advanced JSON Schema validations in its tool calling payloads, which the Google Gemini API does not support. Gateway Error Logs: Invalid JSON payload received. Unknown name "exclusiveMinimum" Unknown name "propertyNames" Unknown name "const" {"severity":"WARNING","level":40,"time":1772173964743,"name":"llmgateway","logging.googleapis.com/trace":"75d7c57c3c015bf8e3b7235411bd179c","logging.googleapis.com/spanId":"cec6d2e9185d4387","logging.googleapis.com/trace_sampled":true,"traceId":"75d7c57c3c015bf8e3b7235411bd179c","spanId":"cec6d2e9185d4387","traceFlags":"1","status":400,"errorText":"{\n \"error\": {\n \"code\": 400,\n \"message\": \"Invalid JSON payload received. Unknown name \\\"exclusiveMinimum\\\" at 'tools[0].function_declarations[0].parameters.properties[6].value': Cannot find field.\\nInvalid JSON payload received. Unknown name \\\"propertyNames\\\" at 'tools[0].function_declarations[13].parameters.properties[1].value': Cannot find field.\\nInvalid JSON payload received. Unknown name \\\"propertyNames\\\" at 'tools[0].function_declarations[13].parameters.properties[2].value': Cannot find field.\\nInvalid JSON payload received. Unknown name \\\"propertyNames\\\" at 'tools[0].function_declarations[16].parameters.properties[3].value': Cannot find field.\\nInvalid JSON payload received. Unknown name \\\"const\\\" at 'tools[0].function_declarations[18].parameters.properties[4].value.any_of[1]': Cannot find field.\\nInvalid JSON payload received. Unknown name \\\"propertyNames\\\" at 'tools[0].function_declarations[18].parameters.properties[8].value': Cannot find field.\",\n \"status\": \"INVALID_ARGUMENT\",\n \"details\": [\n // ... (省略了内部重复的 fieldViolations 详情，上面 message 里的报错已经足够开发者定位了) ...\n ]\n }\n}\n","usedProvider":"google-ai-studio","requestedProvider":"google-ai-studio","usedModel":"gemini-3.1-pro-preview","initialRequestedModel":"google-ai-studio/gemini-3.1-pro-preview","organizationId":"[REDACTED]","projectId":"[REDACTED]","apiKeyId":"[REDACTED]","msg":"Provider error"}