A monochromatic palette — one hue across a wide range of lightness values, plus one or two true accent colors — almost always looks more considered than a five-color palette assembled from "what feels good."

What to do

Pick one neutral hue as your base. Pure gray is fine. A subtle warm gray (slight yellow undertone) or cool gray (slight blue undertone) is better.
Generate 8–12 steps of that hue from near-white to near-black. Tailwind's slate, zinc, stone, gray, and neutral are good starting points. Linear, Vercel, Notion all use this approach.
Pick one true accent for primary actions. Saturated, intentional. Don't dilute it across the UI — earn its use.
Optionally pick one second accent for warnings or success states. These should be subdued, not loud. If the brand accent is green, success takes a different hue, or users can't tell "primary action" from "it worked".

Three derivation rules keep the set coherent: neutrals share the brand's temperature (a blue brand wants cool greys; warm greys fight it, and an untinted #808080 reads as placeholder); light tints come from lowering chroma in OKLCH, not lowering opacity, which greys them out; and disabled gets its own muted token rather than opacity, which passes contrast on one background and fails on the next (color-token-tiers).

That's it. The whole palette is ~14 tokens. Most "design systems" with 60 color tokens are overcomplicating.

What to avoid

Bright purple gradients (any of the purple → indigo → fuchsia variants). Universal AI tell.
Five-color brand palettes with no hierarchy. Every color competes for attention; the eye finds nothing to land on.
Adjacent hues without intent. Red + orange + yellow with no narrative reason is muddy.
High saturation everywhere. Monochrome at 5–10% saturation reads as restrained and confident.

When to apply

Designing a new product UI from scratch.
Refactoring a tokens file that has accumulated 60+ colors.
Reviewing a landing page or PR where the team has added a new accent for "emphasis."

Why this works

The eye can only track 2–3 colors at once. A monochrome palette gives the user a single tonal language to read; the one accent stands out by being the deviation. A multi-color palette dilutes attention — there's nothing to deviate from.

Gotcha

"Monochromatic" doesn't mean "boring." A monochrome palette with rich texture, considered typography (see typography-humanity), and tight motion (see duration-table) feels luxurious. A multi-color palette with bad type and bad motion feels cluttered.

See also dark-mode for the dark-mode variant of these tokens, ai-default-tells for what to remove.

Sources

guidelines.sh — "Monochromatic with subtle accents; avoid bright/purple gradients."
Linear, Vercel, Notion — examples of monochrome-with-one-accent in production.
Emil Kowalski's design-engineering practice, distilled by HKTITAN — status hue, neutral temperature, tints and disabled tokens.