list-principles

THE RISK

Low Risk

Why list-principles needs a policy

This is a simple data retrieval operation that queries and returns predefined reference information from the WCAG 2.2 specification. It performs no modifications, does not execute code or commands, and has no irreversible effects. The read-only nature and minimal blast radius from potential misuse confirm low severity.

From the tool's definition Tool 'list-principles' returns a static list of four WCAG 2.2 principles (Perceivable, Operable, Understandable, Robust) with no side effects, modification, or external execution capabilities.

Documented attack patterns abuse exactly the kind of access list-principles gives an agent:

POLICY

How to control list-principles

PolicyLayer is an MCP gateway — it sits between your AI agents and WCAG MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list-principles:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list-principles": {}
  }
}

list-principles is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register WCAG MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

Related tools and policies

More WCAG MCP Server tools

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All 20 WCAG MCP Server tools →

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
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FAQ

Questions about list-principles

What does the list-principles tool do? +

Lists all four WCAG 2.2 principles: Perceivable, Operable, Understandable, and Robust. It is categorised as a Read tool in the WCAG MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list-principles? +

Register the WCAG MCP Server MCP server in PolicyLayer and add a rule for list-principles: 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 WCAG MCP Server. Nothing to install.

What risk level is list-principles? +

list-principles is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list-principles? +

Yes. Add a rate_limit block to the list-principles 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.

How do I block list-principles completely? +

Set action: deny in the PolicyLayer policy for list-principles. 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.

What MCP server provides list-principles? +

list-principles is provided by the WCAG MCP Server MCP server (joe-watkins/wcag-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every WCAG MCP Server tool call.

Start from WCAG MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →