broadcast_custom_event

THE RISK

High Risk

This tool triggers an external operation by broadcasting data to all connected WebSocket clients. It doesn't merely read or write stored data — it actively pushes an event to connected clients, which could trigger downstream actions in those clients. The blast radius is medium since misuse could disrupt connected clients or trigger unintended behaviors in any listeners.

From the tool's definition Broadcasts a custom event to all WebSocket clients

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

HOW TO CONTROL BROADCAST_CUSTOM_EVENT

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "broadcast_custom_event": {
      "limits": [
        {
          "counter": "broadcast_custom_event_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

broadcast_custom_event stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

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

RATE-LIMIT THIS TOOL →

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EXPLORE

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All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
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FAQ

What does the broadcast_custom_event tool do? +

Broadcasts a custom event to all WebSocket clients. Args: event_data: Data to send with the event. It is categorised as a Execute tool in the OBS MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on broadcast_custom_event? +

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

What risk level is broadcast_custom_event? +

broadcast_custom_event is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit broadcast_custom_event? +

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

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

broadcast_custom_event is provided by the OBS MCP Server MCP server (royshil/obs-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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// WHAT BROADCAST_CUSTOM_EVENT ON OBS MCP SERVER DOES

// THE RISK

// HOW TO CONTROL BROADCAST_CUSTOM_EVENT

// EXPLORE