fw_mute_user

THE RISK

Medium Risk

Why fw_mute_user needs a policy

Muting a user modifies their visibility and notification state — a reversible write action. It does not delete data or break federation, so it's not Destructive. The rate limit and scope (per-user moderation action) suggest medium severity if misused by an AI agent to silence users without consent.

From the tool's definition Mute a user (silence notifications + hide from feeds but keep federation)

Documented attack patterns abuse exactly the kind of access fw_mute_user gives an agent:

POLICY

How to control fw_mute_user

PolicyLayer is an MCP gateway — it sits between your AI agents and Crow, and nothing reaches the server without passing your rules. This is the rule we recommend for fw_mute_user:

policy.json

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

fw_mute_user 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.

Create a free account and register Crow — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about fw_mute_user

What does the fw_mute_user tool do? +

Mute a user (silence notifications + hide from feeds but keep federation). Inline; rate-limited: 5/hour. It is categorised as a Write tool in the Crow MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on fw_mute_user? +

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

What risk level is fw_mute_user? +

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

Can I rate-limit fw_mute_user? +

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

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

fw_mute_user is provided by the Crow MCP server (kh0pper/crow). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Crow tool call.

Start from Crow, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →