Crit Crit

__LBL__

> Item must be kept a secret, and all individuals who discover it are to be killed.

"Killed" is incredibly blunt. It's the right word but not typically used by the Foundation. "Terminated" would be more in accordance with the Foundation's way of speaking. (Unless this is an existing esoteric class, in which case disregard.)

> MTF γ-78

Don't know how I feel about this. Typically MTF designations are shortened using Latin letters rather than Greek (e.g. MTF Rho-2 shortens to MTF R-2). Like, do what you want, but using Greek letters can ruin the pacing.

> When SCP-XXXX is under Foundation custody, attempts are to be made to ensure that the method to access the anomaly is restricted only to individuals within the Foundation.

This is kind of a given? The Foundation, by default, don't provide information about their anomalies to GoIs/non-Foundation people. It's also implied by the Object Class.

> SCP-XXXX is a perfect replica of the Mexica altepetl of Tenochtitlan as it was in late November 1519.

"late November of 1519" might work better; it's a pacing thing.

> The majority of the four zones of SCP-XXXX is accessible to the general public, with the only areas restricted to the original population.

"the only areas"? I feel like you might be missing a word and/or need to reword the sentence here.

> Beyond the city, in Lake Texcoco and the coast, Hernan Cortés' forces can be seen, which consisted of thirteen ships, horsemen, and foot soldiers.

"consists of"

> These forces constantly patrol SCP-XXXX, but never come closer than 5km to SCP-XXXX.

"These forces constantly patrol, but never come closer than 5km to SCP-XXXX." or "These forces constantly patrol the area, but never come closer than 5km to SCP-XXXX."

> Once SCP-XXXX is under Foundation control, Class-A amnestics are to be administered to the populace of Mexico City and the surrounding area. Non-anomalous members of Los Ratones who are captured are to be administered Class F amnestics and released into the general public. Captured Anomalous members of Los Ratones are to be administered both Class-C and Class-G amnestics, with a focus on the events of Operation 1521 and the existence of SCP-XXXX. These members are then to be released in or near known anomalous communities.

Be consistent with amnestic class hyphenations (Class-F vs Class F). Why Class C //and// Class G? If the memories aren't existent anymore, there's no way to make them //seem// non-existent. Why are they released in anomalous communities? Should the Foundation not contain them if they are anomalous?

> Multiple documents from multiple groups have been recovered referring to SCP-XXXX.

Are you planning on writing more documents for Addendum XXXX.2? If not, remove this sentence.

__Overall__

I recommend asking Limeyy to crit this if you haven't already because he knows a lot about Aztecs. Also Cyvstvi (/hj) because this is esoteric (jokes aside, they're a good critter).

Your clinical tone is not great in places. Your description feels like a Tale rather than a skip description. Cut out all repeated and/or irrelevant information.

Be consistent with your Oxford commas etc etc.

Overall, you've got a lot going on. I like the narrative and the conclusion, but I think you focus too much on describing the pocket dimension when most of it is irrelevant to the story. Even Los Ratones aren't relevant in the end, despite being mentioned a lot before the second addendum.