How to Check If Your Cover Letter Sounds AI-Written

TLDR: Em dashes (—), many overcomplicated words in a single sentence, lack of variety and focus on information density, monotonic expressions, conjecture.

The previous blog post was mostly about detection. This will be more about diving into the meat and potatoes of recognizing AI text and characteristics in cover letters.

Why Human Cover Letters Still Matter in 2025

Cover letters are something that employers ask us to write, but actually they might not even open our letters. One can view the cycle as humiliating, to say the least.

There are a few angles to look at this:
a) We give them what they want: a display of our writing skills and train of thought
b) We let the AI write the cover letters, and potentially get flagged for lack of originality

It's true that taking the path A is time consuming, but for the perfect positions that you surely do encounter, I highly encourage you to skip using AI. There are certain job listings that feel like a perfect fit. We all know that for those it's more than ideal to go the extra mile when applying.

Common Mistakes in AI-Written Cover Letters

Structural Markers

Em-dashes: When an AI is asked to write a cover letter (or any other piece of text), they excessively use em dashes. Those are the longest of the lines. These — are almost never used by humans. Back in the day they were in the fancy person's tool bag, but now most of the em dashes you see are written by an AI. You definitely should clear them from your AI-generated cover letters.

Overcomplicated words: There isn't a clear list of them, but words like delve, express, deep-rooted, seamlessly, elevate, hone, eager. You get the idea. Enough of these packed into the text, and it starts to look unnatural.

Complex, monotonic sentence structures: Similar to the previous point, instead of having complex words appear more commonly than in human text, AI tends to keep writing in the same complexity throughout the document. Their language stays monotonous, kind of trying to keep the information density as high as possible.

High information density: AI tends to pick the perfect words for the occasion, to write out the exact meaning that the textual context is looking for. Instead of writing "They said", the AI could write "They expressed". In case the context truly means that the person expressed a feeling or a personal thought, the AI picked the correct way. The verb "Say" is too broad, but that's exactly the point. We humans most often choose good enough words to express ourselves, but AI tends to do that every time. This is how they keep their information density and information accuracy unnaturally high at all times.

Over-polished tone: Think of the middle manager who needs to be presentable, authoritative and official. That's how AIs tend to write when they are given a task to come up with something important, such as cover letters. They try to fit the task perfectly, just to end up writing in an overly complex and extremely polished tone. If a human truly tried, our end-result would be the same, minus ten percent. That ten percent is what I call being human. It's what differentiates us from them.

Semantic Markers

Stock phrasing: Fancy word, basically means someone trying a bit too hard to express sincerity or thoughtfulness, ending up sounding too obvious. Let's take a line "I've always admired your company..." -- This can fly, but anything similar packed into a tight chapter more than once would trigger an alarm in us.

Lack of personal narrative: This is important. The AI can only write using the information you have given to it. They don't have access to your memory about the projects or clients. They completely lack the human part of the story. This is something we would naturally add, even if it just ends up being bits and pieces. Yet it's something we as humans can subconsciously pick out from the text.

Misaligned tone: Since the moment we are born, every day we encounter dozens or even hundreds of expressions that measure sentiment of a person or a subject. These can be in forms of facial expressions to convey feelings, speech that carries out the mood of the speaker, or written text that has hidden clues of tiny nuances. Humans are experts of subtle sentiment analysis. If the AI writes even in a slightly differentiating tone that doesn't match the context, we can pick it up. We just feel weird, and that's the clue.

Artificial transitions: AI can write in an unnatural flow, like "Furthermore, I am passionate about innovation...". These are lines that the majority of humans naturally do not come up with. Transitions are supposed to make the text more fluent. Yet, coming up with a fluent transition can be challenging, depending on the text and context.

What Makes a Human Cover Letter Feel Human-written

Your personal writing style is like your fingerprint. Each of us is unique, and we write in our own way. It's true that for cover letters, we need to take a role to display. This most often feels unnatural. Still, CoverSentry's idea is to divide writers into two groups: AIs and real humans. As the AI revolution keeps progressing, it's getting even more important to play the human role.

So how to make your cover letter sound human?

Add personal touch: You have the experiences and memories in your mind, so add a subtle personal take. In cover letters it's not expected of you, but if done right, a touch of familiarity makes you stand out.

Don't overcomplicate your grammar: There is no need to reach the highest possible density of information in your cover letters. This would just make your text get flagged more easily.

Don't overuse fancy words: Some are okay, but too many make it suspicious and might bring more harm than good.

Even though it might be tempting, adding mistakes or typos purposefully is not ideal. There are situations where strategically placed spelling mistakes increase authenticity, but cover letters should remain flawless.