check_wcag_contrast
utilpeek: Check the WCAG contrast between a text color and a background color. To convert colour formats too use convert_color_check_contrast. Returns the WCAG 2.x contrast ratio of a foreground and a background CSS color, with AA / AAA pass or fail for normal text, large text and UI components (...
This record as markdown: /tools/dev-tanod-tanod/check-wcag-contrast.md
What check_wcag_contrast does on Tanod
AI agents call check_wcag_contrast to retrieve information from Tanod without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
background | string | Yes | The background color it sits on, in the same CSS color formats. |
foreground | string | Yes | The text or UI color, a CSS color: hex (#rgb, #rrggbb, #rrggbbaa), rgb() / rgba(), hsl() / hsla() or a CSS color name. |
Parameters from the server's own tool schema.
Why check_wcag_contrast is rated Low
Even though check_wcag_contrast only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
The rule that runs check_wcag_contrast safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Tanod, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For check_wcag_contrast, this is the rule to start with:
check_wcag_contrast is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Tanod, apply this rule, and every check_wcag_contrast call is checked against it from then on.
Questions about check_wcag_contrast
utilpeek: Check the WCAG contrast between a text color and a background color. To convert colour formats too use convert_color_check_contrast. Returns the WCAG 2.x contrast ratio of a foreground and a background CSS color, with AA / AAA pass or fail for normal text, large text and UI components (unrounded: #777 on white is 4.48:1 and fails AA). An unparseable or out-of-range color is a 422 before any payment (not charged). A translucent color is composited over the background before the contrast is computed. Typically under 0.1 s. Price: USD 0.001. Free: 10 utilpeek calls per IP per UTC day. Docs: https://tanod.dev/learn/color-contrast-checker-api.html. It is categorised as a Read tool in the Tanod MCP Server, which means it retrieves data without modifying state.
check_wcag_contrast accepts 2 parameters: background, foreground. Required: background, foreground. The full parameter table on this page comes from the server's own tool schema.
Register the Tanod MCP server in PolicyLayer and add a rule for check_wcag_contrast: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Tanod. Nothing to install.
check_wcag_contrast is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the check_wcag_contrast rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for check_wcag_contrast. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
check_wcag_contrast is provided by the Tanod MCP server (https://tanod.dev/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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