subscribe · Unfragile MCP: Risk & Policy

WHAT IT DOES

What subscribe does on Unfragile

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

WHY IT NEEDS A POLICY

Why subscribe needs a policy

The subscribe tool creates a new persistent configuration (a watch/subscription) in the system. This is a Write operation because it creates or modifies data in a reversible manner—subscriptions can presumably be cancelled via the unsubscribe tool visible in the sibling tools list.

From the tool's definition Tool description states 'Set up a persistent watch' and 'Get notified daily', indicating creation of a new subscription record that persists in the system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

subscribe Rate-limited

subscribe 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": {
    "subscribe": {
      "limits": [
        {
          "counter": "subscribe_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 Unfragile, so you can run agents against it safely.

FAQ

Questions about subscribe

What does the subscribe tool do? +

Set up a persistent watch for new AI tools matching a query. Get notified daily when something new appears in the Unfragile graph. Requires at least one notification channel (email or webhook). It is categorised as a Write tool in the Unfragile MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on subscribe? +

Register the Unfragile MCP server in PolicyLayer and add a rule for subscribe: 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 Unfragile. Nothing to install.

What risk level is subscribe? +

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

Can I rate-limit subscribe? +

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

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

subscribe is provided by the Unfragile MCP server (savirinc/unfragile-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.