A simple mod that allows admin to create assign custom commands to custom messages. The messages must be added through a command.json file in config/pebbles-command-shortcut. Here's an example config, you can do multiple lines of messages like in the example:

[
  {
    "command": "hello",
    "messages": [
      {
        "message": "Hello, <player>!"
      },
      {
        "message": "Welcome, <rainbow><player></rainbow>! /rtp to get start!"
      }
    ]
  },
  {
    "command": "goodbye",
    "messages": [
      {
        "message": "Goodbye, <player>!"
      },
      {
        "message": "See you later, <rainbow><player></rainbow>!"
      }
    ]
  },
  {
    "command": "vote",
    "messages": [
      {
        "message": "<green>Vote for our server <click:open_url:'https://linktr.ee/dynastyminecraft'><underlined>here</underlined></click> and <blue>gain</blue> <bold>some</bold> <italic><yellow>pebbles</yellow></italic></green>!"
      }
    ]
  },
  {
    "command": "ping",
    "messages": [
        {
            "message": "Pong!"
        }
    ]
  }
]

The codeblock looks a bit messy but if you put it in a normal editor (Notepad++, VSCode etc.) it will look palatable.

Pebble's Custom Command Messages