On the other hand, why bother? Just provide a stat block. Since people in real life, around the table, can't agree on what is good, evil, lawful or chaotic, using those denominations doesn't add anything to the description. Keep the fluff in specific settings. The Xenomorph would be classified as evil by some groups, I'd see them as not aligned -- they are no more evil than sharks or smallpox. What's the point in labelling them with unclear qualifiers?
The MM did that if you read entry on Quaggoths, we learn that "in a distant age, quaggoth tribes dwelled upon the surface as nocturnal arboreal hunters, possessing their own language and culture". That's basically a sentient species. The stories continues... "When elves entered the mortal realm, they clashed with the quaggoths". OK, that's basically a war, it happens all the time even within a species... "eventually driving them to near extinction. Only by fleeing deep into the Underdark did the quaggoth survive". So we had tribes of a sentient species, with language and culture, that was genocided by elves. With a passion, because not only did they have to hide in the Underdark but they had to go DEEP into the Underdark... staying near the surface wasn't enough not to be destroyed by the land-grapping elves, showing sign that they were really intent into exterminating them. I'd be strongly suspicious of ancestor-worshipping elves in this context. TBH, I don't think many people pay attention to the Quaggoth story, but it really paints elves of old into worse than orcs, because the orcs had a reason to be aggressive, while the elves apparently just wanted to take their land.
And frankly, reading the story of the gods conspiring against Gruumsh to take all the places to live and letting nothing for the orcs can be interpreted as just an orcish belief... but it's totally coherent with elves as fantasy nazis claiming their vital territory and driving other people into extinction. It's also make the idea that orcs are evil the same way that "Indians are evil because they don't want to let us take their land" in hollywood westerns, not a very convincing idea of "evil". They are just currently at war with every other race because they were not afforded a place to live in the world. It's certainly a long lasting war, but unless you consider that all war is evil -- in which case most (all?) human cultures are evil, there is nothing inherently evil by being at war. They do sacrifices of their eyes to their god -- that's a religious belief, nothing evil. They take a great pleasure in killing elves -- ok, that's sadistic, admittedly, but after millenia of war I am pretty sure anyone would arrive at the point of hating the soldiers of the other side -- it's not an excuse, though. They are raider and plunderers, but that's not particularly evil by itself, attacking ennemy supply lines is a common and sound practice. They kill "any humanoid that stands against them". That's pretty much the goal of any army. Only the mention of their bloodlust let the reader infer that they might also kill humanoids that don't stand against us, but it's never explicitely written. The mention that they are always on the move isn't evil, it's just a regular practice of nomads. Their habit of attacking "the richest target" proves that they are intelligent. Attacking poor targets yield less gold.
At the next paragraph, I started wondering if it wasn't a case of unrealiable narrator because it's stated that they are "flaunting such vivd and grotesque titles as Many Arrows". The latter is canonically peaceful... And the name isn't grotesque ; it's even sounding very similar to the Broken Arrow tribe of Native Americans.
The next paragraph is even more interesting... "Rejecting notions of racial purity, they proudly welcome ogres, trolls, half-ogres and orogs into their ranks". Who exactly is embracing notions of racial purity in the setting? That would be a sign of enlightenment on the orc parts. If it's mentionned, it's because it's noteworthy, a distinctive trait of them.
Their goddess of fertility ask them to procreate often and indiscriminately. So they must be fruitful and multiply and reject notion of racial purity. Great, that's not something unheard of, especially fitting for a fertility goddess. That, and their babies are orcs or half-orcs, irrespective of the other parent's exact species.
You can read the description as "orcs are evil, plundering, xenophobic, rapists and genocidal maniacs" of course and it might even be the intended effect. But the wording in the MM can be read as "orcs were the butt of the jokes of human, dwarven and especially elvish gods, despite just wanting some place to settle, so they had to become nomadic people and setttled people continues to treat them with a strong anti-nomadic bia, including accusations of all the crimes ranging for "killing and plundering" to "having funny names" to prove that it's justified to kill them. I'd say they are average and maligned by the evil followers of the other gods, the same who exterminated the peaceful quaggoth to take their lands.
Reason: their ancestors were not granted any land to inhabit, so they must survive by plundering, which makes them evil in the eyes of the settled people, regardless of their individual qualities. Even if you're the smart and peaceful Obould Many-Arrow who brokered a peace treaty with all your neighbours, taking the risk of angering your own fighters and being killed for that -- you will still be derided as a "flaunting a grotesque name", the name of your proud ancestors.