WCAG MCP Server

list-guidelines

Retrieve WCAG 2.2 accessibility guidelines with optional filtering by principle to support web compliance implementation.

Instructions

Lists WCAG 2.2 guidelines, optionally filtered by principle number (1-4).

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": "list-guidelines"
  }
}

Input Schema

Name	Required	Description	Default
`principle`	No	Filter by principle number (1=Perceivable, 2=Operable, 3=Understandable, 4=Robust)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Feb 5, 2026

TDQS

A3.7/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden. It states what the tool does but lacks behavioral details such as whether it returns all guidelines at once or uses pagination, what the output format is, or any rate limits. The description is minimal and doesn't compensate for the absence of annotations.

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 a single, efficient sentence that front-loads the core purpose and includes the optional filtering detail. There is no wasted text, and it effectively communicates the essential information in minimal words.

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

Completeness3/5

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

Given the tool's low complexity (one optional parameter, no output schema, no annotations), the description is adequate but has gaps. It covers the purpose and parameter use, but lacks details on output behavior (e.g., format, pagination) which would be helpful for an agent. It's minimally viable but not fully complete.

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 description coverage is 100%, with the parameter 'principle' fully documented in the schema (including enum values and descriptions). The description adds no additional parameter semantics beyond what's in the schema, so it meets the baseline of 3 for high schema coverage.

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 specific verb ('Lists') and resource ('WCAG 2.2 guidelines'), and distinguishes from siblings by specifying the optional filter by principle number. It differentiates from tools like 'get-guideline' (singular) and 'list-principles' (different resource).

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

Usage Guidelines4/5

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

The description provides clear context for when to use this tool (to list guidelines with optional principle filtering), but does not explicitly state when not to use it or name alternatives. For example, it doesn't contrast with 'list-success-criteria' or 'get-guideline' for different needs.

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