Judging a Cover Letter Generator by What It Leaves Blank
A cover letter answers a question your resume does not: why this application, to this employer, from you. That answer requires two inputs no generator holds — what this particular organisation is dealing with, and why you are writing to them rather than to twenty others. So the useful way to assess a generator is not by output quality but by how honestly it handles the gaps. This page recommends no product and scores none.
The artefact is different, so the failure mode is different
Resume generation is mostly a restructuring problem: you have facts, they need ordering and compressing. Cover letter generation is a rhetorical problem: something has to be argued to a specific reader.
That difference explains the most common thing wrong with generated letters. Given your resume and a posting, a model has only those two documents to work from, so it produces the only letter those documents support — a restatement of your resume, arranged in paragraphs, wrapped in enthusiasm. Every sentence is defensible and the letter says nothing, because there was nothing else in the inputs to say.
You can measure this. Take the generated letter and strike out every sentence whose content already appears on your resume. Then strike out every sentence that would be equally true if you sent it to a different employer in the same industry. Read what is left. On a lot of generated letters, almost nothing is.
That surviving remainder is the letter. The rest is packaging.
What only you can put in
The employer’s actual situation. Not their mission statement — their circumstances. A team that has just been formed, a product that just shipped, a market they have publicly said they are moving into, a constraint visible in the posting itself. This is research, it takes ten minutes, and a generator cannot do it because it does not have access to the specific thing and will invent a plausible substitute if pushed. That substitution is the core of what AI does not know about the employer you are writing to.
Your reason. Why this role now, what you are moving toward, what you want to be doing more of. Nobody else has this information, and it is often the only genuinely unique sentence in the whole document.
The awkward thing. A gap, a short tenure, a sideways move, an unfinished qualification. A cover letter is the one place you get to frame these in your own words before anyone else frames them for you. A generator will either ignore the awkward thing entirely or produce a defensive paragraph about it, because it cannot tell which of the two your situation calls for.
Testing a generator without paying for a verdict
Give it only the posting. No resume. A tool that produces a full confident letter from a job posting alone is generating from the posting’s own vocabulary, and you now know what its baseline output really is.
Then add your material and diff the two. How much did your history actually change? If the answer is “the job titles”, the tool is not using your input, it is decorating around it.
Look for questions. The genuinely useful behaviour is a tool that asks — what drew you to this, what do you want them to remember, is there anything in your history you want addressed. Prompts of that kind are the closest thing in this category to a real feature, because they move the work to the person who has the information.
Check the register. Read the output aloud. If it does not sound like a sentence you would say to a colleague, it will not sound like you to a reader either, and a letter is the part of an application where sounding like a person is the point.
Check for invented specifics. Any claim about the company, any figure about you, any statement of experience that was not in your input. These slip in most easily in the enthusiasm paragraph, where a warm sentence can quietly assert something about your background that is not true.
Where the letter and the resume have to agree
Whatever the letter says, someone may put it next to your resume and next to your profile. If your letter narrates a coherent motivation your resume contradicts, the contradiction is the thing that gets noticed. Keeping one story across resume, profile, and interview is more important than any single document being impressive.
There is a related trap in workflow: pasting your resume in and asking for a letter guarantees you get the resume back in prose. Starting from your reasons instead, and using the resume only for factual reference, produces a different draft — which is the argument for not feeding your resume into the cover letter prompt at all.
Why there is no winner here
Every product in this category is doing the same underlying thing with the same limitation: no access to the employer, no access to your motivation, no way to tell which of your history is relevant to a reader it cannot see. Ranking them would be ranking interfaces while calling it advice.
If a generator gets you past a blank page, that is a real benefit and worth something. Just keep the ratio in mind: the parts that make a letter worth reading are the parts you supply, and no amount of shopping changes the split.