The phrase "an essential addition" is correct and usable in written English.
It can be used when describing something that is necessary or important to include in a particular context or situation.
Example: "The new software update is an essential addition to our existing system, enhancing its functionality and security."
Alternatives: "a crucial component" or "a vital enhancement."
If you have rough grass and want to keep it interesting into summer, this is an essential addition.
A celebration of Albers's legendary achievements, this beautiful publication is an essential addition to any serious art library.
When it comes to dealing with Kiev, de facto control over an autonomous, unstable Crimea could prove to be an essential addition to Putin's separatist toolbox.
"For these reasons, the leverage ratio is an essential addition to the Bank's toolkit for improving the stability of the financial system.
Baked beans may be an essential addition to a fry-up, though Guardian reader favourite AA Gill calls them "de trop" in The Wolseley's breakfast book.
This is an essential addition to the literature because the vast array of adverse impacts caused by heatwaves2,5,35,36 are due to their distinctive characteristics.
Another Little Piece of My Heart is a genuinely essential addition to the bibliography of the revolutionary 60s.
Spanish pimentón — the sweet, smoked kind — is a nice but not essential addition — you could use any paprika or mild chile powder instead.
Having settled upon your ingredients, which in my case are ground beef, the controversial sausage or ground pork, bread soaked in milk (essential addition I think a giving a nice bready plumpness), parsley, mint (if you have it), a flick of nutmeg, parmesan or pecorino, salt (steady if you have added a seasoned sausage), pepper and a whole egg.
Nikon's motion snapshots may not be an essential new addition to the world of photography, but easy panoramas definitely are.
Called the Bioforce, this control pad promises all the familiar buttons and functions found in most controllers, but with one essential addition: electric shock.
