One good example.

“Make it warm but professional” is a fog. Two people will hear two tones. An example is a thing the agent can copy the shape of.

Paste one piece you already like. Say what to copy from it: length, warmth, or structure — not “the vibe.”

You are writing a welcome note for a weekend workshop.
Match the tone and length of this example, not the topic:
“Bring a pencil. We will start at ten, late is fine for the first ten minutes, and there is tea on the back table.”
Write the note for a Saturday drawing class.

Swap the example for a sentence you actually like. Keep the instruction: match tone and length, not topic.

One example that does the work adjectives cannot. Save examples the way you save good sentences.