Object Class: Safe
Only "Object Class:" should be bold: "Object Class: Safe"
Special Containment Procedures:
SCP??-1/2/3 and 4…
This should all be one line: "Special Containment Procedures: SCP??-1/2/3 and 4…" Same goes for the Description.
SCP??-1 should be marked with a visual warning at all times to inform employees of its manipulative nature.
Use "is to be" instead of "should be" for better tone.
luckily SCP??-1 is not often succesful in this due to the absurdity of its claims and obvious lying.
"luckily" isn't detached tone. Even if everyone reading holds the same opinion, you need to write without input. In journalism, the popular saying is, "You should be able to write about a hurricane as though you weren't trying to hurt its feelings." The same holds true here.
"successful", not "succesful".
I'd use "falsehoods" instead of "lying". It sounds a bit more scientific.
SCP??-2 is described by employees as a philosofic mind.
"philosophic", not "philosofic".
Employees that are exposed to philosofic speech by SCP??-2 for more than 15 minutes often report feeling bored and tired
Read above.
horn like growths emerging from the back, top and both sides of it's head.
Hyphenate "horn like": "horn-like".
"it's" is a conjunction of "it" and "is". The word you're looking for is the possessive: "its".
Due to the nature of SCP??-3, Foundation Staff concidered upgrading conainment of all SCP?? objects
"considered", not "concidered".
"containment", not "conainment".
SCP??-4 also often directs its insults at an individuals mother
"individuals" means "more than one individual". Use the possessive: "individual's".