Personal Tricorder

Personal Tricorder is an incredibly important tool. New players always start with it. Even if you lose it, you have a spare Tricorder in your Ship Locker. You can also craft and/or buy a replacement.

It gives access to the following (left-click):
 * Research (here you "unlock" the recipes to craft new items)
 * Information about player, bonuses/penalties of the chosen race, temporary immunities, Status effects, etc.
 * Tool to create mobility Techs like Microsphere or Phase Sprint, and tool to equip them.
 * Tool to refuel your Mech.
 * Tool to replace weapons, thrusters, etc. on your Mech.
 * Tool to upgrade all weapons/armors (for Upgrade Modules, up to tier 6) and tools (for Manipulator Modules, to the maximum tier that the tool supports).
 * Codex reader (it's more convenient than usual codex reader of Starbound, and also doesn't truncate long pages).

It also gives access to Tutorial quests (right-click). Not only can they be a guidance to new player, they also have some good rewards. It's a good idea to sometimes check if your current situation (discovered resources, etc.) allows you to complete some of them.

It also allows to configure the Matter Manipulator (hold Shift and left-click) - for example, temporarily reduce 5x5 mining area to 2x2 when you are building delicate houses and don't want to accidentally remove the blocks that you don't intend to remove.