mail-tool in Cursor IDE is installed but stating No tools.

Following this tutorial "Coding Your Own Custom MCP Server in Python - Full Tutorial" I was not able to see  the MCP mail-tool in Cursor IDE activated: It stays red, stating No tool.  Any idea what the cause is.

<img width="478" height="271" alt="Image" src="https://github.com/user-attachments/assets/af941bd6-71ef-449f-9bf1-6ced0bfda0e9" />