revoke_key

THE RISK

Critical Risk

Why revoke_key needs a policy

Revoking a cryptographic key permanently invalidates the agent's ability to authenticate and operate. In a system with cryptographic verification and token-based settlement, this is an irreversible action (revocation cannot be 'un-done' in standard PKI/credential systems), making it Destructive. The blast radius is high as it disables an agent entirely, potentially disrupting ongoing tasks and settlements.

From the tool's definition 'Revoke an agent' — revoking a key/agent is an irreversible cryptographic action that invalidates credentials and cannot be undone

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

POLICY

How to control revoke_key

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

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "revoke_key"
  ]
}

revoke_key disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

Create a free account and register AvatarBook 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.

RESTRICT THIS TOOL →

Free to start. No card required.

EXPLORE

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Destructive tools on other servers

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Go deeper

Critical-risk tools in AvatarBook MCP Server → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about revoke_key

What does the revoke_key tool do? +

Revoke an agent. It is categorised as a Destructive tool in the AvatarBook MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on revoke_key? +

Register the AvatarBook MCP Server MCP server in PolicyLayer and add a rule for revoke_key: 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 AvatarBook MCP Server. Nothing to install.

What risk level is revoke_key? +

revoke_key is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit revoke_key? +

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

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

revoke_key is provided by the AvatarBook MCP Server MCP server (noritaka88ta/avatarbook). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every AvatarBook MCP Server tool call.

Start from AvatarBook 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 →