Here is a small dialog and four ways to ask an agent to improve it. Tap each one and watch what the agent does with your words:

The agent heardAdd a gradient, a glow and a bounce. Make everything brighter.

Upgrade to Pro?

You have used 3 of 3 free projects.

Not nowUpgrade

Button text contrast 2.6:1 · below 4.5:1

The vaguer the words, the more the agent guesses. Its guess is the average of everything it has seen.

"Make it pop" got a gradient, a glow and a button that grew. The agent did exactly what you asked. The problem is you did not ask for anything in particular, so it filled the gap with the most common idea of "pop" it knows.

Vague words get average results

An agent cannot see what you see. When you say "make it pop", it has to guess what "it" is and what "pop" means, and its best guess is the middle of everything it was trained on. That middle has a name in this course: AI-default UI.

The fix is not a longer prompt. It is a more exact one.

✕ A wish

"Make the button pop."

✓ A spec

"Raise the contrast of the primary button's text to 4.5:1. Keep the secondary button quiet."

The second one names which element, what property and how much. There is nothing left to guess, so there is nothing to get wrong.

What design vocabulary is

is the set of exact names for how interfaces look and move. Designers use these words to talk to each other quickly; you can use them to talk to an agent precisely.

A few you will meet soon:

You might say	The exact word	What it means
"the text is hard to read"		How much darker the text is than its background. 4.5:1 is the minimum for body text.
"the letters are squished"	tracking	The space between all the letters in a line
"the menu feels slow"		How speed changes during an animation: fast start, gentle stop
"the numbers jump around"	tabular figures	Digits that are all the same width, so columns line up
"the main button"		The one thing you most want people to do on this screen

You do not need to memorise them. You need to know they exist, so that when something feels off you can look up its name. The vocabulary page collects every term in this course, each with a phrase you can hand an agent.

Point, don't describe

Sometimes the best word is no word at all. Telling an agent "the blue button in the sidebar" sends it searching through your files. Showing it the exact thing sends it straight there.

Name the file
"In src/components/PlanCard.tsx…" beats "on the pricing page".
Show a picture
A screenshot with a circle around the problem beats a paragraph describing it.
Link a reference
"Make the hover like Linear's sidebar" beats five adjectives.

Point at the exact thing, then name exactly what is wrong with it. The philosophy module goes deeper, including tools that let you click an element and hand the agent its exact address.

The precise version is often plainer

Precision is not jargon. "The button has no hover state" is precise and plain. "The affordance lacks an interactive feedback layer" is just harder to read. Use the shortest words that leave nothing to guess.

When you are stuck for the word, ask the agent: "what is it called when…". The skill has a verb for exactly that.

Find the word· for your agent

/design-engineering name: the numbers in my pricing table shift sideways when they change. What is this called, and what is the exact CSS fix?

And when you know what you want, say it like a spec:

A precise request· for your agent

On the upgrade dialog, make the primary button's text contrast at least 4.5:1 against its background, keep "Not now" as a quiet text button, and change nothing else. Tell me the contrast ratio before and after.

Quick check

Which request will an agent most reliably get right?

Vague words get average results

What design vocabulary is

Point, don't describe

The precise version is often plainer

Connected lessons