Mistakes in spelling or grammar can torpedo an otherwise great article. Grammarly is a popular online tool for catching them. I use the free version regularly to check articles before submitting them. It does a decent job at catching the worst of my blunders. It hasn’t impressed me enough to go for the paid version, too. It has its quirks, being obsessive on some issues and plain wrong on others.

Mokka sternly protecting a dictionary. December 30, 2008.

Here are a few of the ways Grammarly is excessively strict or just weird, with real examples:

Demanding articles before nouns.

My text: A big advantage of the new software is speed of compilation.
Grammarly: Use “the speed” or “a speed.”

Grammarly insists on articles before many noun phrases. I haven’t figured out the pattern. In this case, “the speed of compilation” would be OK, but it sounds off to my ear, which I trust more than Grammarly. “A speed” is wrong, of course. There’s certainly no grammatical rule that requires an article before every noun phrase. If you feel shy about using a naked phrase, you could use “its speed of compilation,” though there’s no need to.

Odd notions about commas.

My text: It’s difficult to say how often this has happened, since clear evidence is often lacking.
Grammarly: Remove the comma.

Grammarly dislikes commas before subordinate clauses. It’s wrong. They aren’t necessary in short sentences, but leaving out the comma in this sentence would make it hard to read.

There’s a discussion on Stack Exchange on whether a comma is needed before a subordinate clause. English doesn’t have a clear rule on this. The closest thing to a rule is to insert a comma if you’d naturally make a pause while speaking. In reading the example sentence aloud, I definitely pause before “since.”

It’s a tough case to bring under an algorithm. You’re better off following your own judgment than removing all the commas Grammarly frowns upon.

My text:Obviously you can’t try out every possibility.
Grammarly: Put a comma after “Obviously.”

Grammarly wants a comma after any introductory adverb. This is another tough case to put under a general rule. Purdue OWL’s discussion of “Commas after Introductions” says, “Introductory elements often require a comma, but not always.” The cases where you should use a comma include “if there is a distinct pause” and “to avoid confusion.” In this case you might or might not pause after “obviously.” The comma makes the sentence look choppy to me. Certainly nothing mandates it.

Prepositional confusion

My text: The benefits to everyone’s health increase constantly.
Grammarly: Use “of,” not “to.”

I had to twiddle this sentence to get it to trigger an error message. Grammary is perfectly happy with “The benefits to everyone’s health are great.” It’s somehow parsing the sentence in a way that requires “of,” which makes it meaningless. Prepositions are tricky things. We know the right one to use only because we (native speakers, that is) have used them all our lives. Grammarly often catches incorrect use of them, but it makes a lot of mistakes in this area.

Plain nonsense

My text: An error message will appear regardless of what other action is taken.
Grammarly: Change “other” to “another.”

Sometimes I can’t even guess where Grammarly’s recommendations come from. There’s no way to make sense of “what another action is taken.” Oddly, if I change it to “what other action you take,” it doesn’t object. The English language is complicated, and sometimes Grammarly gets completely confused.

A tool, not an oracle

Don’t get me wrong. Grammarly is useful. The free version isn’t annoying. (I use an ad blocker, so I can’t say whether it’s annoying if you don’t have one.) It catches a lot of errors. But you’re a writer and know how to write, right? You don’t make a U-turn on the Interstate just because a GPS tells you to, do you? Your judgment comes first. If you’re uncertain, check a grammar reference or style guide. If a colorful wording is appropriate to your work, stick with it. Don’t change what you’ve written just to satisfy an application.

Here’s another review of Grammarly that sums up its pros and cons.