Install languagetool (with todos / questions)

Right now I've a custom service in
~/.config/systemd/user/languagetool-server.service:

    [Unit]
    Description=LanguateTool Server

    StartLimitBurst=3
    StartLimitInterval=400

    [Service]
    Restart=on-failure
    RestartSec=2s

    ; This should work, but doesn't seem to work: https://www.freedesktop.org/software/systemd/man/systemd.resource-control.html
    ; Maybe due to legacy control group hierarchy version 1?
    ; MemoryMax=3%
    Environment="JAVA_TOOL_OPTIONS=-Xmx256m"
    ExecStart=/home/daniels/.nix-profile/bin/languagetool-http-server --port 8081 --allow-origin "*"

    [Install]
    WantedBy=default.target

Unsure how I can generate the service file.

overlays/my-packages/default.nix

@@ -12,6 +12,9 @@ self: super: {
       self.litecli
       self.mkcert
 
+      # Writing
+      self.languagetool
+
       # Media
       self.vlc
     ];