Can you move and act with the Ready action?

Question

I am trying to understand the Find Familiar spell and its interaction with the Ready action.

The PHB reads about Ready:

First, you decide what perceivable circumstance will trigger your reaction. Then, you choose the action you will take in response to that trigger, or you choose to move up to your speed in response to it.

When the Ready action says "you choose the action ... or you choose to move", is this an exclusive or inclusive or? Can the reaction include movement with an action, e.g. "The moment any monster comes around the corner, I will run at it and stab with my sword"?

For context, I am wondering if a familiar can move to deliver a touch spell on its reaction, as mentioned under the Find Familiar spell:

Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it.

Answer 1

Exclusive Or

The rules on the ready action read:

First, you decide what perceivable circumstance will trigger your reaction. Then, you choose the action you will take in response to that trigger, or you choose to move up to your speed in response to it.

In common English, "or" used in this sense is an XOR. You can you have soup or salad but not both. So, you can either move, or you can take an action.

Designer's Intent

A tweet by rules designer Jeremy Crawford agrees with this reading:

When you use Ready, you prepare an action or a move, not both.

So, in the case of a familiar, a reaction spent channeling a spell excludes it from moving away from the target.

Ready the Action for the Familiar's Turn

If you Ready the Touch spell on your turn for the trigger "When my familiar moves in range...", the familiar can use its reaction during its turn (as opposed to its master's turn). If it is close enough it could continue its movement after the reaction was complete. It would also have it's action, which it could use for things like the Help action to distract one of the enemies.

Answer 2

If the Ready action allowed both movement and another action, it would totally break the action economy because it would allow this:

"I move 30 feet away from the orc, then I take the Ready action. When Bob says 'Now!', I'll fire an arrow at the orc, and move another 30 feet away from it."

Speaking is a free action that you can take when it's not your turn, so Bob will just say "Now!" as soon as I finish my normal movement. I've just effectively gained an extra 30 feet of movement at the lesser cost of consuming my reaction.

Here's another example of how this interpretation could be exploited:

"I move 30 feet across the field, then I take the Ready action. When Bob says 'Now!', I'll take the Dash action and move my speed, which will be 60 feet, across the field."

Again, Bob will say "Now!" while it's still my turn, so even if you were to argue that the Dash action doesn't increase your speed, only grants you extra movement, and thus doesn't increase the amount of movement you'd supposedly get from the Ready action's "move up to your speed"; even then, it's still your turn when Bob speaks, so you'd be able to just use Dash's bonus movement normally instead. Either way, you effectively got to move 3x your speed in one turn.

Because both of those scenarios lead to being able to do more in one turn than you could otherwise do, it's clear that Ready should not allow both movement and another action.

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Now, with all that being said - as a DM, I've proposed the following house rule to my group, with the caveat that I may add one or more limitations, or fully rescind it, without notice, if at any time I feel that it doesn't play well:

If you don't use all of your movement on your turn, you can use whatever movement remains along with the action chosen from your Ready action.

Possible limitation #1: you cannot do this if you chose the "move up to your speed in response" option for Ready.
Possible limitation #2: it's all or nothing; you can only do this if you don't use any movement during your turn.
Possible limitation #3: when you use this option, for the remainder of the encounter, your initiative order changes to the position in which your reaction takes place (like 3.5's Delay action).

However, we have not yet tested this house rule. If and when we do, I can update this answer with the results.