Raycast script command to send a Messages.app IM to a fixed contact, or just switch to Messages if no argument is provided. Don't forget to customize `theEmail`.

send_im.sh

#!/usr/bin/env osascript

# Required parameters:
# @raycast.schemaVersion 1
# @raycast.title Send IM
# @raycast.mode silent

# Optional parameters:
# @raycast.icon 💬
# @raycast.author Henrik Nyh
# @raycast.argument1 { "type": "text", "placeholder": "message", "optional": true }

on run argv
  -- Customize this.
  set theEmail to "foo.barson@example.com"

  set theMessage to (item 1 of argv)

  if length of theMessage is greater than 0 then
    tell application "Messages" to send theMessage to buddy theEmail of (service 1 whose service type is iMessage)

    -- Toast output.
    "Sent: " & theMessage
  else
    tell application "Messages" to activate

    -- Toast output.
    "Switching to Messages"
  end
end