SCP Foundation

and is to be checked for instances of SCP-XXXX-A daily.

While this is technically reasonable, remember that the Foundation is not constantly refilling the cell with brand new objects to perfect, nor are said objects appearing inside the cell. That is, there's only so much SCP-XXXX can perfect in a confined cell. It might be better to instead say that new items must be inspected/approved before being introduced into SCP-XXXX's cell.

When outside of it's containment cell, SCP-XXXX is to be both blindfolded and restrained until it has reached the destination.

No SCP wouldn't be restrained en route to a new location. Blindfolding(vision obstructing if you want to be super-duper-technical) is tailored specifically to your SCP's ability so it works.

All instances of SCP-XXXX-A are to be studied and, if the instance in question holds no use to the foundation, are to be incinerated.

This sentence feels a bit odd. I would recommend breaking it up. "All instances of SCP-XXXX-A are to be confiscated and studied. Instances holding no use to the Foundation are to be incinerated."

If it holds use then said instance is to be used for it's appropriate purpose.

We'll address this line among others in the concept check.

SCP-XXXX is a English man currently thirty-four (34) years of age and is standing at about six (6) meters in height.

Avoid using the "number (x)" formatting as it's usually reserved for pill dosage amounts and not simple age counting. As far as actual content, I have no idea what this individual looks like. I can't really picture age and I can't picture height. In-universe, this means that should SCP-XXXX breaks out, recovery teams will only be able to identify your SCP(if it's thrown on a disguise) by measuring its height and figuring out its accent. Try to create a description that is satisfying both to the imaginations of your readers, and also to the Foundation officials reading your article.

"Experiment 021: The perfectionist".

"perfectionist" should be capitalized as part of a title.

When SCP-XXXX sees something as imperfect it will become agitated and attempt to "fix" it.

Considering even an unloaded pistol is considered just as imperfect as a bent spoon, you really need to nail down, even roughly at least, what criteria your SCP uses to judge something imperfect.

To do this SCP-XXXX will attempt to simply come in contact with the object in question causing it to instantaneously become able to complete whatever purpose it's existence holds, with relative perfection.

The way this is written implies that SCP-XXXX doesn't even have to succeed in making contact with the object to perfect it; it just has to make an attempt. Tighten your sentences. "become able to complete whatever purpose it's existence holds" sounds far more philosophical than scientific. I would recommend, at least for now, replacing this with "become able to fulfill their intended purpose." This gets into wonky stuff conceptually, so we'll revisit this line in the concept check as well.

until three (3) days after it's seventeenth (17) birthday

Again, avoid the number(x) style. Replace "it's" with "its."

When questioned SCP-XXXX explains that this event lead to it's ability but has no memory of the entity responsible.

Tense jerks from past tense to present tense. Be consistent.

Exactly why did we do this? I know we have to test the limits of SCP-XXXX's effect, but why a spoon?

This is awfully melodramatic. Scientists routinely do a ton of boring, control tests before making a single, 'practical' test. Personally, it makes perfect sense to do some testing with simple objects like this instead of just jumping to things like the glock.

When used, the bullet shot would always kill the target, this is achieved by the use of teleportation

I imagine you're trying to say the bullet teleports into the person aimed at. This could be made more clear.

The subject was instantaneously restored to perfect health, and whenever the subject died a clone of them with all their memories would appear out of thin air within seconds.

Not going to lie, this sounds a lot like Connor from the "Confined" series. I only just discovered the series, but the similarity is very apparent. As I highly doubt the 'purpose' of a human being is to never die, you can even preserve the consistency in your article by cutting this out.

I wasn't the biggest fan of this. Concept-wise, this reads as a humanoid 914 who can go around bestowing anything with anomalous super-powers. Another big issue comes from the fact that you state SCP-XXXX perfects objects so they can fulfill their purpose. But this is extremely muddy water. The purpose of human life, which is what you're building up to, is extremely controversial and you already have one reader(me) who will argue that it is not to live forever. This can be remedied by tightening the criteria and restrictions on what can be perfected, and by how much.
I believe this draft will need a lot of work before it gets published. Try running the base concept of this thing through the brainstorming forum and IRC for progression forward. Good luck!