🐛 MCP Bug: AI Assistant Generates Invalid Tool Calls for notion-update-page

[vitaly-arkhipov-1]

Problem

The AI assistant generates incorrect MCP tool calls for notion-update-page, causing infinite loops and validation errors.

Error

MCP error -32602: Invalid arguments for tool notion-update-page: Expected object, received string

Root Cause

AI assistant wraps MCP tool arguments in a data field as a string instead of passing them as direct object properties.

Expected:

{
  "page_id": "123",
  "command": "update_properties", 
  "properties": {...}
}

Actual (Incorrect):

{
  "data": "{\"page_id\":\"123\",\"command\":\"update_properties\",\"properties\":{...}}"
}

Impact

• ❌ Notion MCP integration completely broken
• ❌ AI assistant gets stuck in retry loops
• ❌ Must disable MCP Notion to continue working

Environment

• Cursor 1.7.38
• macOS 24.6.0
• Notion MCP Cloud Server

Steps to Reproduce

1. Configure Notion MCP in Cursor
2. Ask AI to update a Notion page
3. AI generates tool call with wrapped data field
4. MCP validation fails before network request
5. AI retries with same incorrect format
6. Infinite loop occurs

Technical Notes

• No network requests visible in DevTools (validation fails before network)
• MCP server working correctly
• Issue is in AI assistant's MCP call generation logic
• Affects all MCP tools, not just Notion

Priority

HIGH - Blocks core MCP functionality

Request

Please fix the AI assistant's MCP tool call generation to pass arguments directly instead of wrapping them in a data field.

---

Reporter: @vitaly
Date: 2025-01-08

[devonpmack]

+1 it seems cursor is unable to format the data correctly

[Edison-A-N]

This appears to be an auto-model issue where Cursor selects a small model that can't understand complex Notion block structures, causing parameter generation errors. Similar issues occur in other apps (e.g., https://github.com/makenotion/notion-mcp-server/issues/108), but work fine with larger models like GPT-5.

[jensenity]

notion sucks with cursor!!