Colour contrast

An MCP tool from the Developer Toolbox server, hosted on mcp.hjlabs.in.

Compute the WCAG 2.x contrast ratio between two hex colours and report pass or fail against AA and AAA thresholds for normal and large text.

Name on the gateway: devtools__colour_contrast · read-only.

Parameters

Name	Type	Description
`foreground` required	`string`	Foreground colour as #rgb or #rrggbb.
`background` required	`string`	Background colour as #rgb or #rrggbb.

Through the Smart Gateway, any client can run it by name with call_tool, or let the gateway find it with search_tools:

call_tool arguments

{
  "name": "devtools__colour_contrast",
  "arguments": {
    "foreground": "…",
    "background": "…"
  }
}

Or connect the Developer Toolbox server directly, which lists 18 tools including this one:

Run in your terminal

claude mcp add --transport http hj-devtools https://mcp.hjlabs.in/mcp/devtools \
  --header "Authorization: Bearer YOUR_API_KEY"

Use the colour contrast tool with foreground set to ….