From a background or class or even as one of your starting items, thieves’ tools may have been listed as one of your proficiencies. Its exact nature might not have been obvious to you.
What are Thieves’ Tools?
Here are the tools that thieves use according to DnD 5e’s Basic Rules:
It includes a small file, a set of lock picks, a metal handle-mounted mirror, a set of narrow-bladed scissors, and a pair of pliers. When you are proficient with one of these tools, you can add your proficiency bonus to any ability check you make for disarming traps or opening locks.
There are several items that thieves use in a variety of ways, and proficiency with the toolset lets you use your proficiency bonus to open locks and disarm nonmagical traps.
Despite their absence of specifics, it’s probably best to assume that your lock picks are sufficient for the majority of locks, and that you have a variety to choose from.
Tools and proficiency of thieves
We all know that proficiency with a set of tools allows you to add a bonus to your roll when using those tools, but sometimes it is unclear what this bonus means in-game. For example, you might wonder whether proficiency is necessary to use thieves’ tools.
With thieves’ tools, any character can pick a lock or disarm a trap.
I recommend, however, that if the lock or trap is complex. Even with thief’s tools it will be impossible to open or disarm it without proficiency.
You can pick a simple or standard lock pretty easily if you understand the general theory behind lockpicking. Although it sometimes takes me up to ten minutes to open ordinary locks, I can usually do it without any training or experience.
My ability to open advanced locks is very limited. And those who are experts in lockpicking are often able to do so in about the same amount of time it takes to use a key.
One of those experts would be someone who is skilled with thieves’ tools. They can pick locks and disarm traps that someone lacking proficiency in thieves’ tools would tinker with all day but never accomplish.
In addition, they are faster than most people. If the Wizard is able to pick the lock to the mansion door. It will take them 10x as long as the Rogue.
A lock can only be opened by true masters without thieves’ tools.
Gaining proficiency with thieves’ tools
There are a number of ways to become proficient with thieves’ tools.
The tools can be learned through your class so that you have a proficiency in them. The Rogue and the Artificer classes both gain proficiency in thieves’ tools by default.
This proficiency can be acquired by choosing a background. This skill is granted by criminal, urchin, and urban bounty hunter backgrounds.
When you gain a feat, you can select the Skilled feat to gain proficiency with thieves’ tools.
Last but not least, you can train to become proficient with thieves’ tools if your DM allows it.
It takes 250 days and 1 gp per day to gain this proficiency according to the Player’s Handbook.
By the end of the training period, you are proficient in the tool. The trainer must be willing to spend time teaching you the new proficiency in order for you to be able to train this way.