tsserver protocol is missing notification message type. (maybe?)

While implementing a tsserver client, I found out not all request messages will reply with a response.
For example, the open request extends the Request interface. But it really notifies (as the documentation implies).
This was a bit confusing for me, because I understood that if I send an open request, I must wait for the response... but it never came.
https://github.com/microsoft/TypeScript/blob/a2609b1f1b58f9b6ef62cb3b6ff47efb35059eee/lib/protocol.d.ts#L1113-L1124

I understand that the interface documentation says the server will not send a response. I didn't read the full command documentation until now.
But maybe the documentation could be a bit more explicit about a kind of message where a response is not expected, for certain commands (maybe notify?).