Color adjust lightness

color-adjust-lightness · version 1.0.0 · Geometry, location & color · free, no key needed

Lightens or darkens a CSS color by percentage points of HSL lightness and returns a hex color.

Use when you need to: lighten a hex color by 20 percent · darken a CSS color by 10 percent · increase HSL lightness.

Decide before calling

Read the versioned contract and the supported scope below. Reuse color-adjust-lightness@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use color-adjust-lightness@1.0.0 for lighten a hex color by 20 percent. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• lighten a hex color by 20 percent
• darken a CSS color by 10 percent
• increase HSL lightness
• make #336699 lighter
• reduce color lightness
• adjust color brightness in HSL
• lighten an rgb color

Not supported

• convert named colors
• color name lookup
• rgba and hsla function aliases
• mix colors in perceptual spaces
• adjust CSS relative colors

Behavior

• Converts sRGB to HSL by CSS Color 4 section 7, adds percentage/100 to lightness, clamps to [0,1], then converts back.
• The percentage is an absolute percentage-point change, not multiplication of current lightness.
• Returns lowercase hex, retaining alpha when it is below one, plus standard_version.
• Accepted function names are rgb(), hsl(), and hwb(); rgba(), hsla(), and CSS named colors are unsupported. Alpha channels are accepted inside the supported function names or hex notation.

Input

• color (string, required): min length 1; max length 128
• percentage (number, required): min -100; max 100

Output

• standard_version (string, required)
• format (one of "hex", "rgb", "hsl", "hwb", required)
• value (string, required)

Limits

• max input bytes: 256
• max color bytes: 128
• max items: 2
• max iterations: 1
• max output bytes: 256

Example

Request input:

{
  "color": "#336699",
  "percentage": 20
}

Response:

{
  "result": {
    "standard_version": "CSS Color 4 (2024-02-14); WCAG 2.2",
    "format": "hex",
    "value": "#6699cc"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "color-adjust-lightness",
  "version": "1.0.0",
  "input": {
    "color": "#336699",
    "percentage": 20
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/color-adjust-lightness/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"color":"#336699","percentage":20}'

The machine-readable contract is at /v1/tools/color-adjust-lightness/versions/1.0.0.

CLI

node cli.mjs run color-adjust-lightness 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

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