pubsub.unsubscribe · MCP: Risk & Policy

WHAT IT DOES

What pubsub.unsubscribe does on Mcp

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

WHY IT NEEDS A POLICY

Why pubsub.unsubscribe needs a policy

Unsubscribing removes a subscription, which is a reversible write operation (the user could re-subscribe). It does not irreversibly destroy data in the destructive sense, nor does it directly move money. The description is truncated, lowering confidence slightly.

From the tool's definition 'remove one of YOUR subscriptions' — reversibly deletes a subscription record owned by the caller

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

pubsub.unsubscribe Rate-limited

pubsub.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": {
    "pubsub.unsubscribe": {
      "limits": [
        {
          "counter": "pubsub.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 Mcp, so you can run agents against it safely.

FAQ

Questions about pubsub.unsubscribe

What does the pubsub.unsubscribe tool do? +

PUBSUB: remove one of YOUR subscriptions by its. It is categorised as a Write tool in the Mcp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on pubsub.unsubscribe? +

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

What risk level is pubsub.unsubscribe? +

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

Can I rate-limit pubsub.unsubscribe? +

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

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

pubsub.unsubscribe is provided by the MCP server (@2sio/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.