If you wish to check what Grapevine parses from your game's MSSP data, you can use this checker.

Grapevine follows the guidelines set on the TinTin++ MSSP docs page.

In order for this check to work, your game must send the IAC WILL MSSP telnet option or respond to mssp-request at the login prompt. Grapevine will send the term type Grapevine if the game requests it.

If your game does not send IAC WILL MSSP, Grapevine will send mssp-request\n after 10 seconds. Grapevine will wait 20 seconds before giving up.