set_output_directory · MCP ScreenCatch MCP: Risk & Policy

WHAT IT DOES

What set_output_directory does on MCP ScreenCatch

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

WHY IT NEEDS A POLICY

Why set_output_directory needs a policy

This is a configuration write operation that changes a setting (output directory path) but does not create captures themselves, execute code, destroy data, or involve financial operations. It is reversible—the directory can be changed again at any time. The blast radius is minimal since it only affects where future captures are stored, not their content or deletion. This is a low-severity Write operation.

From the tool's definition Tool description states it 'Set[s] the directory where screen captures will be saved' - a configuration change that modifies where data is written without deleting or executing external commands.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_output_directory Rate-limited

set_output_directory 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_output_directory": {
      "limits": [
        {
          "counter": "set_output_directory_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches MCP ScreenCatch, so you can run agents against it safely.

FAQ

Questions about set_output_directory

What does the set_output_directory tool do? +

Set the directory where screen captures will be saved. It is categorised as a Write tool in the MCP ScreenCatch 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_output_directory? +

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

What risk level is set_output_directory? +

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

Can I rate-limit set_output_directory? +

Yes. Add a rate_limit block to the set_output_directory 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_output_directory completely? +

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

set_output_directory is provided by the MCP ScreenCatch MCP server (johnelamont/mcp-screencatch). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.