Can an echo knight's echo interact with objects?

Question

The echo is apparently tangible and occupies a space, but is it capable of doing something as simple as opening a door? Can it pick up and carry anything?

Answer 1

No.

The description for the Echo Knight's echo has a discrete list of things that the Knight may do using its echo:

[...] you can mentally command the echo to move up to 30 feet in any direction (no action required).

You can use the echo in the following ways:

[...] you can teleport, magically swapping places with your echo at a cost of 15 feet of your movement, regardless of the distance between the two of you.

When you take the Attack action on your turn, any attack you make with that action can originate from your space or the echo’s space. [...]

[...] you can use your reaction to make an opportunity attack [...]

At level 7, the Knight may also hear/see from an echo's location but at no point is the echo given ability to interact with the environment in the ways you describe.

One thing that I see a lot of people get confused about is the fact that the echoes are not independent agents from the Echo Knight. That is, the echoes never do anything unless the Knight does it through/using them. The echoes can't even attack: notice that it is the Echo Knight who attacks and uses them as the source for the attack.

So if an Echo Knight wanted her echo to open a door, she would have to first teleport to the echo's location and then open the door herself.

Answer 2

Not necessarily RAW; but they should be able to open doors

Firstly I will say that Rykara does a good job of covering the key words in the rules, and RAW I do agree with them. But the DM is allowed (encouraged, even intended) to interpret those rules for their own games.

I personally can't get my head around how the fighter can use the duplicate to deliver a sword blow, fire a gun or otherwise manipulate a weapon, but can't open a door.

However you want to flavour the ability of the fighter to attack from the echos position* the fact is that during that time they can affect things (mostly enemies hit points) and it just makes sense that they can also do simple actions such as open a door.

Carrying things is different, because they don't stay in th echos space, just act from it, so quick things are ok, but eventually they will no longer be able to hold that effect, so they probably can pick things up, but would drop them pretty quickly as the fighter can't stay in their echo.

*I have known people imagine the fighter temporarily appearing in that square, attacking and then leaving, or the echo becoming tangible briefly, the exact flavour seems vague.