README should include the -c flag.

[FGasper]

The current inline help is:

usage: cli.js [-h] [-v] [-l PORT] [-b] [-c] [-R SENDRESIZE] [-r] [-H HEADER]
              [-n] [-k] [-d] [-s SUBP]
              [address]

Positional arguments:
  address

Optional arguments:
  -h, --help            Show this help message and exit.
  -v, --version         Show program's version number and exit.
  -l PORT, --listen PORT
                        Start a websocket server on PORT.
  -b, --binary          Use binary WebSockets.
  -c, --report-close    Write WebSocket $close:$reason to STDERR on close.
  -R SENDRESIZE, --send-resize SENDRESIZE
                        Send text frame when client terminal resizes, using
                        template string containing ${columns} and ${rows}.
  -r, --raw             Use rawmode stdin.
  -H HEADER, --header HEADER
                        Specify a custom HTTP request header. May be given
                        multiple times.
  -n, --no-check        Do not check for unauthorized certificates.
  -k, --keep-open       Do not close the socket after EOF.
  -d, --deflate         Use per-message deflate.
  -s SUBP, --subprotocol SUBP
                        WebSocket subprotocol

… which contains parameters (e.g., -c) that the project’s README doesn’t include.

The same goes for the npmjs.org entry for this project: https://www.npmjs.com/package/wscat2