accessibility-mcp-server

validate_aria

Validate ARIA attributes in HTML snippets, checking for valid values and known roles, and listing required attributes with WCAG references.

Instructions

Validiert ARIA-Attribute in einem HTML-Snippet.

Prueft: aria-* Attribute auf gueltigen Werten, role-Attribute auf bekannte Werte, required ARIA-Attribute fuer bestimmte Rollen.

Args: html_snippet: HTML-Code-Snippet (kein vollstaendiges Dokument noetig)

Returns: Liste der ARIA-Probleme mit WCAG-Referenz

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "html_snippet": "<html_snippet>"
    },
    "name": "validate_aria"
  }
}

Input Schema

Name	Required	Description	Default
`html_snippet`	Yes

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0May 29, 2026

TDQS

A4/5.0

Behavior3/5

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

No annotations are provided, so the description carries full burden. It declares what is checked but does not disclose behavioral traits such as whether it modifies input or requires authentication. The read-only nature is implied but not explicit, and no side effects are noted.

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

Conciseness5/5

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

The description is concise, beginning with a clear one-sentence purpose, followed by bullet points of checks, then args and returns sections. Every sentence adds value, with no redundancy or filler.

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?

With only one parameter and an existing output schema, the description covers the key aspects: purpose, input, and output format. It does not address limitations or edge cases, but for a simple validation tool, it is sufficient.

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

Parameters4/5

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

The schema has 0% description coverage, yet the description adds meaningful context: it clarifies that html_snippet expects an HTML snippet (not a full document) and provides a German explanation. This compensation justifies a score above baseline of 3.

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 explicitly states it validates ARIA attributes in HTML snippets, specifying three checks (aria-* values, role values, required ARIA for roles). This clearly distinguishes it from sibling tools like check_color_contrast or check_heading_structure.

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 ARIA validation but does not explicitly state when to use it versus alternatives like check_form_labels. No exclusions or prerequisites are provided, leaving the agent without clear guidance on when not to use it.

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

Deploy Server