I am suggesting that the staff of Snapcraft implement a /trade plugin. A trade plugin would allow players to trade with each other in a pop up GUI once the trade has been initiated. I would recommend this plugin https://www.spigotmc.org/resources/trading.1203/ as it is has the most customization options such as the players having to be in a 10 block radius to initiate a trade which is good for game modes such as factions and will also prevent trade spamming for across the world. It is very simple to use with few commands;
/Trade (PlayerName) - Requests a trade with the designated player
/Trade Accept - Accepts the current trade request
/Trade Decline - Declines the current trade request
It also reduces the risk of being scammed as you'll click the green wool to indicate you are ready. Once the both players have done so, a 5 second countdown will begin where no players can change the traded items. If you have second thoughts, cancel the trade by clicking the red wool. If you both like the selection of items, leave the inventory alone until the countdown is over. Both players will receive their traded items at the exact same time. This plugin would be a great addition.
/Trade (PlayerName) - Requests a trade with the designated player
/Trade Accept - Accepts the current trade request
/Trade Decline - Declines the current trade request
It also reduces the risk of being scammed as you'll click the green wool to indicate you are ready. Once the both players have done so, a 5 second countdown will begin where no players can change the traded items. If you have second thoughts, cancel the trade by clicking the red wool. If you both like the selection of items, leave the inventory alone until the countdown is over. Both players will receive their traded items at the exact same time. This plugin would be a great addition.