add-subscriber · Paragraph MCP: Risk & Policy

WHAT IT DOES

What add-subscriber does on Paragraph MCP

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

WHY IT NEEDS A POLICY

Why add-subscriber needs a policy

The tool creates a new data entry (subscriber record) in the publication system. This is a write operation: it modifies state reversibly (subscribers can be removed). It is not destructive (not irreversible), not execute (does not run arbitrary code or external operations), not financial (does not move money), and not read (creates rather than retrieves data).

From the tool's definition Tool description states 'Add a subscriber to your publication' - this creates a new subscriber record, a reversible modification to the publication's subscriber list.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add-subscriber Rate-limited

add-subscriber 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": {
    "add-subscriber": {
      "limits": [
        {
          "counter": "add-subscriber_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 Paragraph MCP, so you can run agents against it safely.

FAQ

Questions about add-subscriber

What does the add-subscriber tool do? +

Add a subscriber to your publication by email or wallet address. Requires API key. It is categorised as a Write tool in the Paragraph 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 add-subscriber? +

Register the Paragraph MCP server in PolicyLayer and add a rule for add-subscriber: 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 Paragraph MCP. Nothing to install.

What risk level is add-subscriber? +

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

Can I rate-limit add-subscriber? +

Yes. Add a rate_limit block to the add-subscriber 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 add-subscriber completely? +

Set action: deny in the PolicyLayer policy for add-subscriber. 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 add-subscriber? +

add-subscriber is provided by the Paragraph MCP server (paragraph-xyz/paragraph-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.