The Keeper.sh MCP server is now listed in the official MCP Registry. MCP clients that look servers up in the registry can find Keeper.sh there and connect to it at https://www.keeper.sh/mcp.
Connecting works the same way as adding the server by hand. You approve the connection in your browser, and the assistant can then read your synced calendars and, with your permission, make changes.
The MCP server docs list every tool an assistant can use and how to connect one.