Hey, thanks for the report. This is a known issue with MCP parameter serialization, there’s a very similar thread here: Cursor Auto-Selected Model Stringifies MCP Tool Parameters.
Quick question: are you using auto model selection, or a specific model (like Sonnet or Opus)? In the previous report, the bug only showed up with auto selection, while explicitly selecting a model worked correctly.
If you’re using auto selection, try explicitly selecting Sonnet or Opus as a temporary workaround. If you’re already on a specific model and still hitting the issue, that would be new and important info.
The team is aware of this category of issues. Your report helps with prioritization.