subscribe_topic · USCardForum MCP Server MCP: Risk & Policy

WHAT IT DOES

What subscribe_topic does on USCardForum MCP Server

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

WHY IT NEEDS A POLICY

Why subscribe_topic needs a policy

Based on the tool name 'subscribe_topic', it most likely creates or modifies a subscription/notification preference for a topic, which is a reversible write action. This aligns with the server's description mentioning 'authenticated actions like notifications and bookmarks.' However, the empty description significantly lowers confidence. It is unlikely to be Destructive or Financial given the forum context.

From the tool's definition Tool name: subscribe_topic — description is empty and uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

subscribe_topic Rate-limited

subscribe_topic 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_topic": {
      "limits": [
        {
          "counter": "subscribe_topic_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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

FAQ

Questions about subscribe_topic

What does the subscribe_topic tool do? +

subscribe_topic. It is categorised as a Write tool in the USCardForum MCP Server 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_topic? +

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

What risk level is subscribe_topic? +

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

Can I rate-limit subscribe_topic? +

Yes. Add a rate_limit block to the subscribe_topic 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_topic completely? +

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

subscribe_topic is provided by the USCardForum MCP Server MCP server (raidenrock/uscardforum-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.