send_stream_caption

THE RISK

High Risk

This tool triggers an external operation — injecting caption text into an active stream output. It affects a live broadcast visible to viewers, making it an Execute-level action. Misuse (e.g., injecting inappropriate or misleading captions) could have moderate impact on viewers, hence medium severity.

From the tool's definition Sends CEA-608 caption text over the stream output

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

HOW TO CONTROL SEND_STREAM_CAPTION

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 send_stream_caption:

policy.json

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

send_stream_caption 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 →

Free to start. No card required.

EXPLORE

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High-risk tools in OBS MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

What does the send_stream_caption tool do? +

Sends CEA-608 caption text over the stream output. Args: caption_text: Caption text to send. 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 send_stream_caption? +

Register the OBS MCP Server MCP server in PolicyLayer and add a rule for send_stream_caption: 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 send_stream_caption? +

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

Can I rate-limit send_stream_caption? +

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

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

send_stream_caption 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 SEND_STREAM_CAPTION ON OBS MCP SERVER DOES

// THE RISK

// HOW TO CONTROL SEND_STREAM_CAPTION

// EXPLORE