liveness_check

THE RISK

Low Risk

Why liveness_check needs a policy

This tool performs analysis/verification of biometric data (a selfie) and returns liveness scoring information. It has no side effects—it does not create, modify, delete, or financially commit to anything. The 'spoofing signals' are analytical outputs, not state changes. While biometric data is sensitive, the tool itself is passive and informational.

From the tool's definition Tool name 'liveness_check' and description 'Passive liveness on a selfie (no comparison image). Returns liveness_score + spoofing signals.' indicates a READ operation that analyzes a supplied image and returns computed metrics without modifying data, creating…

Documented attack patterns abuse exactly the kind of access liveness_check gives an agent:

POLICY

How to control liveness_check

PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Ap2, and nothing reaches the server without passing your rules. This is the rule we recommend for liveness_check:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "liveness_check": {}
  }
}

liveness_check 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 Mcp Ap2 — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

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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 →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about liveness_check

What does the liveness_check tool do? +

Passive liveness on a selfie (no comparison image). Returns liveness_score + spoofing signals. POST /v1/biometrics/liveness. It is categorised as a Read tool in the Mcp Ap2 MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on liveness_check? +

Register the Mcp Ap2 MCP server in PolicyLayer and add a rule for liveness_check: 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 Mcp Ap2. Nothing to install.

What risk level is liveness_check? +

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

Can I rate-limit liveness_check? +

Yes. Add a rate_limit block to the liveness_check 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 liveness_check completely? +

Set action: deny in the PolicyLayer policy for liveness_check. 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 liveness_check? +

liveness_check is provided by the Mcp Ap2 MCP server (@codespar/mcp-ap2). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Mcp Ap2 tool call.

Start from Mcp Ap2, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →