prepare_device · Phantom MCP: Risk & Policy

WHAT IT DOES

What prepare_device does on Phantom

AI agents invoke prepare_device to trigger actions in Phantom. 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 prepare_device needs a policy

This tool triggers multiple device state changes (dismissing keyboard, clearing clipboard, resetting status bar, forcing keyboard layout) on a real device or emulator. These are external operations that modify device state, fitting the Execute category.

From the tool's definition Prépare le device actif pour une session de test propre : dismiss keyboard, clear clipboard, reset status bar overrides, force keyboard QWERTY (iOS)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

prepare_device Rate-limited

prepare_device 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": {
    "prepare_device": {
      "limits": [
        {
          "counter": "prepare_device_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 Phantom, so you can run agents against it safely.

FAQ

Questions about prepare_device

What does the prepare_device tool do? +

Prépare le device actif pour une session de test propre : dismiss keyboard, clear clipboard, reset status bar overrides, force keyboard QWERTY (iOS). Tout est opt-out via flags. Auto-appelé par set_device sauf si skip_setup=true. It is categorised as a Execute tool in the Phantom MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on prepare_device? +

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

What risk level is prepare_device? +

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

Can I rate-limit prepare_device? +

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

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

prepare_device is provided by the Phantom MCP server (nthimpulse/phantom-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.