Leonardo da Vinci Wrote One in 1482. The Cover Letter Has Been Reinvented Several Times Since.
In 1482, Leonardo da Vinci wanted to work for Ludovico Sforza, the future Duke of Milan. He did not simply send a portfolio of his paintings. He wrote a letter detailing ten things he could build: portable bridges, armored vehicles, cannon, siege machines, covered wagons, and methods for draining moats. Almost as an afterthought, in the final point of the letter, he mentioned his skill as a sculptor, a painter, and a bronze caster. The letter is preserved today in the Codex Atlanticus at the Biblioteca Ambrosiana in Milan, and historians describe it as the earliest recognizable cover letter. It was addressed to a specific employer, it enumerated skills in relation to that employer's specific needs (Sforza was engaged in military campaigns), and it asked for a job. Leonardo secured the position and remained at Ludovico's court for nearly twenty years.
The format did not spread widely for another four hundred years. The modern cover letter as a standard employment practice emerged in the 1930s, first in finance, where letters were used to provide narrative context for financial documents sent to clients. The convention migrated into hiring during the same decade as formalized corporate employment grew. By the 1950s, American job advertisements were actively requesting cover letters as part of formal applications. The conventions that career counselors taught through the twentieth century, a three-paragraph structure opening with the target role, mapping skills to requirements, and closing with an interview request, codified an approach that had emerged from business letter writing conventions rather than from research on what actually worked in hiring.
Email changed the form factor but not the template. The arrival of applicant tracking systems (ATS) in the 2000s introduced a new dimension that the 1930s version had not faced: automated keyword screening before any human read the application. Despite predictions that digital hiring tools would eliminate cover letters entirely, the format has held on. Research from Employment Hero found that hiring managers are 53 percent more likely to invite a candidate to interview when a tailored cover letter accompanies the application. A separate survey found that 72 percent of hiring managers still expect a cover letter even when the job posting marks it as optional.
What the ATS Problem Actually Is
The introduction of applicant tracking systems changed how cover letters need to be written without changing how they need to read. A well-written cover letter must pass automated keyword screening before it reaches a human reader, then must actually engage that human reader when it arrives.
Over 99 percent of recruiters use keyword filters in their ATS to identify candidates worth reviewing, according to data from Jobscan. The same technology that accelerates hiring for recruiters means that a letter written in general terms, without mirroring the specific language in the job posting, may be filtered out before anyone reads it. The words "project management" and "project coordination" are not synonyms to a keyword filter. If the job posting uses "project management," the cover letter should use "project management."
This creates a specific writing challenge. The letter needs enough keyword density to pass screening, but cannot read like a keyword list to the human who reads it after. The solution is to use the job posting's specific language when describing your experience and skills, then to write the surrounding sentences as actual prose. The keywords appear naturally in context rather than being listed. This satisfies the automated stage without making the letter unreadable at the human stage.
Eighty-eight percent of employers believe they lose qualified candidates to ATS screening errors, according to the same Jobscan research. Applicants are filtered out because their resumes and letters use different but equivalent terminology for the same skills. This is a systems problem, but the burden of working around it falls on the applicant.
The Three Elements That Make a Letter Work
Research on what hiring managers actually respond to in cover letters points to three consistent factors.
First, specificity about the company and role. A letter that contains the company's actual name and a specific reason for applying to that company rather than a competitor is more memorable than a generic letter. Hiring managers report being able to identify templated letters quickly because they contain phrases that could apply to any employer. The candidate who names something specific about the company's work demonstrates genuine interest and reduces the chance of seeming like a mass applicant.
Second, one or two concrete examples of relevant past work, described in terms of results rather than activities. "I managed marketing campaigns" describes an activity. "I managed three email campaigns that generated a combined 180 new leads over six weeks" describes a result. The difference matters because it gives the hiring manager a specific data point to remember.
Third, brevity. Most hiring managers read many applications during a hiring cycle. A letter that makes its case in three or four short paragraphs respects that constraint. A letter that runs to a full page of dense prose asks for more attention than the reader can give it.
These three factors map closely to what da Vinci did in 1482. He named the specific employer. He provided concrete examples of what he could do (an "infinite number of bridges," specific siege machines). And he kept it short. The structure that career counselors have taught for decades is a correct approximation of these factors, but the standardized language that accumulates around it undermines the specificity that makes the structure work.
The Phrases That Appear in Every Letter
There is a documented vocabulary of cover letter phrases that appear in tens of thousands of applications and have lost their communicative value through repetition. Phrases like "I am a highly motivated individual," "I am passionate about this opportunity," "I believe I would be an excellent fit for this role," and "I would welcome the opportunity to discuss my qualifications further" are not wrong. They are simply empty of information. Every candidate believes they are motivated. Every candidate believes they would be a good fit. Repeating those claims without evidence wastes the letter's limited space.
The alternative is to replace each claim with a specific that implies the general quality. Instead of "I am highly motivated," describe one project you worked on after hours or one problem you solved without being asked to. Instead of "I am passionate about this opportunity," name one thing the company has done that made you want to apply. The specifics do more persuasive work than the claims, and they are far less likely to appear identically in the other letters the hiring manager reads the same day.
The ATS generation of job applications has made these phrases more common, not less, because candidates are writing to be safe rather than to be remembered. The keyword optimization instinct generalizes to a risk-averse writing style where saying something potentially wrong feels more dangerous than saying nothing specific. The result is letters that are technically sound and informationally empty.
When Cover Letters Are Not Read
Some hiring processes do not read cover letters at all, or read them only for finalists. High-volume entry-level hiring, roles that process thousands of applicants, and some large corporate recruiting pipelines treat cover letters as optional formalities. In these contexts, the letter's primary audience is the ATS, and the primary goal is keyword matching.
Understanding the hiring process for a specific role is useful before deciding how much effort to invest in the letter. A startup hiring its third employee is likely reading every word of every application. A Fortune 500 company posting an entry-level role with hundreds of applicants may have the hiring manager see only five letters after ATS screening. The letter that reaches the startup founder should be different from the letter that needs to clear an ATS first.
For roles where the cover letter will definitely be read by a human, the investment in specificity pays directly. For roles where ATS screening is the first filter, keyword matching is the precondition and human readability is the secondary objective. Most positions fall somewhere between those poles, which is why a letter that achieves both is more valuable than one that optimizes for only one.
Conclusion
ToolHQ's cover letter generator builds a draft starting from your specific role, background, and target job. The specificity that makes a cover letter work is in the draft from the beginning, rather than something you need to add to a generic template after the fact. The challenge da Vinci solved in 1482 remains the same: making a specific person believe that your particular set of skills is worth attention, in a format brief enough to actually be read.
Frequently Asked Questions
Do hiring managers still read cover letters?
Research suggests 72 percent of hiring managers expect a cover letter even when applications mark it optional, and tailored letters increase interview chances by 53 percent, according to Employment Hero data.
What is the origin of the cover letter format?
The modern cover letter emerged in 1930s finance before migrating to employment applications. The oldest known example is a letter Leonardo da Vinci wrote to the Duke of Milan in 1482 detailing his skills.
How long should a cover letter be?
Most career guides recommend three to four short paragraphs. Hiring managers reading many applications spend limited time per letter, so conciseness matters more than comprehensiveness.