open_url

THE RISK

High Risk

This tool triggers an external operation (opening a URL) in a simulator environment. The effects depend on the URL argument — it could launch apps, trigger deep links, or load web content. This is an execution of an operation rather than a simple read or write, and misuse could cause unintended actions within the simulator.

From the tool's definition Open a URL in a simulator

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

HOW TO CONTROL OPEN_URL

PolicyLayer is an MCP gateway — it sits between your AI agents and Xcode, and nothing reaches the server without passing your rules. This is the rule we recommend for open_url:

policy.json

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

open_url 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 Xcode — 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

More Xcode tools

Destructive delete_file Deletes a file or directory within allowed directories. Destructive remove_swift_package Removes a Swift Package dependency from the active project. Destructive reset_simulator Reset a simulator by erasing all content and settings Destructive pod_deintegrate Deintegrate CocoaPods from the active project, removing all traces of CocoaPods. Execute build_spm_package Builds a Swift Package Manager package directly using Execute build_swift_package Builds a Swift Package using Swift Package Manager. Execute clean_swift_package Cleans the build artifacts of a Swift Package. Execute compile_asset_catalog Compiles an asset catalog (.xcassets) using actool

All 69 Xcode tools →

Execute tools on other servers

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Go deeper

High-risk tools in Xcode → 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 open_url tool do? +

Open a URL in a simulator. 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 open_url? +

Register the Xcode MCP server in PolicyLayer and add a rule for open_url: 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 open_url? +

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

Can I rate-limit open_url? +

Yes. Add a rate_limit block to the open_url 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_url completely? +

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

open_url 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.

Enforce policy on every Xcode tool call.

Deterministic rules across all 69 Xcode tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.

GOVERN XCODE →

Free to start. No card required.

69 Xcode tools catalogued and risk-classified — across an index of 42,500+ MCP servers.

// WHAT OPEN_URL ON XCODE DOES

// THE RISK

// HOW TO CONTROL OPEN_URL

// EXPLORE