open_sim · Sl Test MCP: Risk & Policy

WHAT IT DOES

What open_sim does on Sl Test

AI agents invoke open_sim to trigger actions in Sl Test. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why open_sim needs a policy

This tool launches an external application (iOS Simulator), which is an execution action that triggers an external operation. It has no direct data read/write but causes a side effect by starting a process on the host system.

From the tool's definition Opens the iOS Simulator app

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

open_sim Rate-limited

open_sim 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.

View as policy code

policy.json

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

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about open_sim

What does the open_sim tool do? +

Opens the iOS Simulator app. It is categorised as a Execute tool in the Sl Test MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on open_sim? +

Register the Sl Test MCP server in PolicyLayer and add a rule for open_sim: 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 Sl Test. Nothing to install.

What risk level is open_sim? +

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

Can I rate-limit open_sim? +

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

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

open_sim is provided by the Sl Test MCP server (sampsonky/xcodebuildmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.