eds-mcp-server

Overview Schema Source Related Servers Discussions Admin

Contrast report

contrast_report

Checks WCAG 2.1 contrast ratios for design token foreground-background pairs in light or dark themes, classifying AA, AA-large, AAA and listing failures.

Instructions

The WCAG 2.1 contrast ladder for the token set in both themes (or one): foreground tokens over backgrounds with AA / AA-large / AAA classification and a failures list. The machine version of the Accessibility Lab contrast checker.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "contrast_report"
  }
}

Input Schema

Name	Required	Description	Default
`theme`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.17.0Jul 29, 2026

TDQS

A3.9/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden. It discloses that the tool produces a contrast ladder with classifications and failures, indicating a read-only compute report. However, it does not explicitly state it is non-destructive or describe any side effects. The context is sufficient for a report tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences; the first is dense and informative, while the second ('machine version...') adds context but is somewhat vague. It is reasonably concise but could be tightened to remove minor redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the simple input (one optional enum) and no output schema, the description sufficiently explains the output: a contrast ladder with AAA/AA/AA-large classification and failures. It does not specify the output format (e.g., JSON, text), but for a report tool this is acceptable. Overall, it provides complete context for the tool's functionality.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0%, so the description must compensate. The description mentions 'both themes (or one),' which partially explains the optional parameter. However, it does not explicitly state the effect of omitting the parameter (e.g., defaults to both) or describe the enum values. The compensation is adequate but not complete.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool generates a WCAG 2.1 contrast ladder for tokens, with classification and a failures list. It uses specific verbs and resources ('contrast ladder') and distinguishes itself from sibling tools like 'audit_accessibility' or 'get_tokens' by focusing specifically on contrast ratios.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage for checking token contrast compliance and mentions being the 'machine version of the Accessibility Lab contrast checker,' but it does not explicitly state when to use this tool versus alternatives like 'audit_accessibility' or 'compliance_check.' No when-not or alternative guidance is provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.