unsubscribe · Agent Bus MCP: Risk & Policy

WHAT IT DOES

What unsubscribe does on Agent Bus

AI agents use unsubscribe to create or update resources in Agent Bus — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Agent Bus environment.

WHY IT NEEDS A POLICY

Why unsubscribe needs a policy

Unsubscribing removes a subscription/membership record, which is a reversible write operation. The agent can re-subscribe later, so it is not destructive. Blast radius is low as it only affects channel membership for this agent on a local message bus.

From the tool's definition Remove this agent from a channel

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

unsubscribe Rate-limited

unsubscribe stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "unsubscribe": {
      "limits": [
        {
          "counter": "unsubscribe_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Agent Bus, so you can run agents against it safely.

FAQ

Questions about unsubscribe

What does the unsubscribe tool do? +

Remove this agent from a channel. It is categorised as a Write tool in the Agent Bus MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on unsubscribe? +

Register the Agent Bus MCP server in PolicyLayer and add a rule for unsubscribe: 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 Agent Bus. Nothing to install.

What risk level is unsubscribe? +

unsubscribe is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit unsubscribe? +

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

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

unsubscribe is provided by the Agent Bus MCP server (mustaphasteph/agent-bus). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.