Bug Description

When creating Notion database entries using the notion-create-pages tool with date properties in expanded format, the Date columns appear completely empty in the Notion UI, despite the API returning successful creation responses.

Environment

• Tool: notion-create-pages (MCP)
• Notion API Version: 2022-06-28
• Date: September 16, 2025
• Impact: Critical - Date columns appear empty in Notion UI

🐛 Problem Description

When creating Notion database entries using the MCP (Model Context Protocol) notion-create-pages tool with date properties, the Date columns appear completely empty in the Notion UI, despite the API returning successful creation responses.

Symptoms

• ✅ notion-create-pages returns successful response
• ❌ Date column shows empty in Notion UI
• ❌ Only partial date properties saved (date:PropertyName:is_datetime only)
• ❌ Missing crucial date:PropertyName:start field in fetch results

Steps to Reproduce

1. Create a database entry with date properties using expanded format:

{
  "properties": {
    "Activity": "Test Activity",
    "date:Date:start": "2025-10-10",
    "date:Date:is_datetime": 0
  }
}

2. Check the created entry using notion-fetch
3. Observe that only "date:Date:is_datetime": 0 persists
4. Verify in Notion UI that Date column appears empty

Expected Behavior

Both date:Date:start and date:Date:is_datetime should persist, and the date should display correctly in Notion UI.

Actual Behavior

Only date:Date:is_datetime persists; date:Date:start is silently dropped, resulting in empty date columns.

Root Cause Analysis

The notion-create-pages MCP tool silently drops the date:PropertyName:start field during creation, while preserving other expanded date properties like date:PropertyName:is_datetime. This appears to be a MCP serialization issue where the tool incorrectly processes expanded date properties.

Evidence

✅ Working Example (using different property name):

{
  "date:Day:start": "2025-07-26",
  "date:Day:is_datetime": 0
}

❌ Broken Example (same format, different property name):

{
  "date:Date:is_datetime": 0
  // Missing: "date:Date:start" field silently dropped!
}

Workaround

Use notion-update-page instead, which works correctly:

1. Create entry without dates using notion-create-pages
2. Update with dates using notion-update-page:

{
  "page_id": "created-page-id",
  "command": "update_properties", 
  "properties": {
    "date:Date:start": "2025-10-10"
  }
}

Related Issues

This appears related to the serialization bugs mentioned in:

• Issue Parameter serialization bug: Object parameters received as strings in create-pages and move-pages tools #82: Parameter serialization bug
• Issue update-pages automatically parses the body object as a string in Claude Desktop. #67: Update-pages parsing bug

Additional Details

Schema Evidence

The SQLite schema shows all required fields, but only some are saved:

"date:Date:start" TEXT,          -- ❌ NOT SAVED by create-pages
"date:Date:end" TEXT,            -- ❌ NOT SAVED by create-pages  
"date:Date:is_datetime" INTEGER  -- ✅ SAVED by create-pages

Impact Assessment

• Affected: All date properties in any Notion database using notion-create-pages
• Scope: All expanded property formats (date:X:start, date:X:end, etc.)
• Workaround: Use two-step process (create then update) until fixed

Testing Results

• Before Fix: notion-fetch shows only "date:Date:is_datetime": 0
• After Fix: notion-fetch shows both "date:Date:start": "2025-10-10" and "date:Date:is_datetime": 0