set_source_visibility · Obs MCP: Risk & Policy

WHAT IT DOES

What set_source_visibility does on Obs

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

WHY IT NEEDS A POLICY

Why set_source_visibility needs a policy

This tool is categorized as Write rather than Read because it performs a reversible modification to scene state (toggling source visibility). It is not Destructive because visibility changes are fully reversible. It is not Execute because it doesn't run arbitrary code or trigger external operations—it simply sets a boolean property.

From the tool's definition The tool 'set_source_visibility' modifies the state of a source in OBS Studio by showing or hiding it. The description explicitly states it can 'Show or hide a source,' which is a state modification operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_source_visibility Rate-limited

set_source_visibility 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": {
    "set_source_visibility": {
      "limits": [
        {
          "counter": "set_source_visibility_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 Obs, so you can run agents against it safely.

FAQ

Questions about set_source_visibility

What does the set_source_visibility tool do? +

Show or hide a source in a scene. It is categorised as a Write tool in the Obs MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_source_visibility? +

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

What risk level is set_source_visibility? +

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

Can I rate-limit set_source_visibility? +

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

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

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