run_xcrun · Xcode MCP: Risk & Policy

WHAT IT DOES

What run_xcrun does on Xcode

AI agents invoke run_xcrun to trigger actions in Xcode. 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 run_xcrun needs a policy

This tool allows running arbitrary Xcode tools through xcrun, which can compile code, run scripts, execute build phases, or invoke system commands. The effects are entirely argument-dependent and could include building malicious code, modifying system state, or executing arbitrary shell commands. This is a classic Execute category risk with high blast radius if an AI agent misuses it without proper constraints.

From the tool's definition Tool description states 'Executes a specified Xcode tool via xcrun'. The verb 'executes' and the use of xcrun (which can invoke arbitrary Xcode and system tools) indicates code/command execution with effects dependent on the arguments provided.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

run_xcrun Rate-limited

run_xcrun 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": {
    "run_xcrun": {
      "limits": [
        {
          "counter": "run_xcrun_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 Xcode, so you can run agents against it safely.

FAQ

Questions about run_xcrun

What does the run_xcrun tool do? +

Executes a specified Xcode tool via xcrun. It is categorised as a Execute tool in the Xcode MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on run_xcrun? +

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

What risk level is run_xcrun? +

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

Can I rate-limit run_xcrun? +

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

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

run_xcrun is provided by the Xcode MCP server (xcode-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.