Bug Description

The notion-update-page tool improperly escapes user mentions (<mention-user> tags) when updating page content. User mentions that exist in the original content are converted to escaped strings like \\{\\{user://...\\}\\} instead of preserving the proper <mention-user url="{{user://...}}"/> format.

Steps to Reproduce

1. Create or identify a Notion page with action items containing user mentions (e.g., <mention-user url="{{user://1f9d872b-594c-81cc-8948-0002e98318dd}}"/>)
2. Use the notion-fetch tool to read the page - confirms mentions display correctly as <mention-user> tags
3. Use the notion-update-page tool with replace_content_range command to update a section containing user mentions
4. Fetch the page again with notion-fetch to observe the result

Expected Behavior

User mentions should be preserved in their original format (<mention-user url="{{user://...}}"/>) and display correctly as user mentions in the Notion UI.

Actual Behavior

After updating, user mentions are escaped and appear as:

• \\{\\{user://1f9d872b-594c-81cc-8948-0002e98318dd\\}\\} in the fetched content
• Plain text in the Notion UI instead of clickable user mentions

Investigation & Additional Context

• The issue occurs even when the new content string includes properly formatted <mention-user> tags
• Multiple consecutive updates compound the escaping (e.g., {{{{https://...}}}})
• The notion-fetch tool correctly reads and displays <mention-user> tags from original content
• Only notion-update-page causes the escaping - suggests the issue is in how the update tool processes or serializes the content before sending to the Notion API
• This makes it impossible to programmatically update pages with action items or task lists that have user assignments without breaking the user mentions

Example

Original content (from notion-fetch):

- [ ] <mention-user url="{{user://1f9d872b-594c-81cc-8948-0002e98318dd}}"/> We need a story for table-body-skeleton

After using notion-update-page (from subsequent notion-fetch):

- [ ] \\{\\{user://1f9d872b-594c-81cc-8948-0002e98318dd\\}\\} We need a story for table-body-skeleton

Environment

• MCP Server: notion-mcp-server (official)
• Client: Claude Code
• Notion API version: Latest