Open an app from the home screen by name.
AI agents invoke open_app to trigger actions in Vphone. 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.
Opening an app triggers an external operation on the iOS virtual machine — it launches a process/application. This goes beyond simply reading data; it causes a state change (an app becomes active) and can have downstream effects depending on which app is launched. It fits the Execute category as it triggers an external operation on a controlled device.
From the tool's definition Open an app from the home screen by name
Documented attack patterns abuse exactly the kind of access open_app gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Vphone, and nothing reaches the server without passing your rules. This is the rule we recommend for open_app:
{
"version": "1",
"default": "deny",
"tools": {
"open_app": {
"limits": [
{
"counter": "open_app_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}open_app 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.
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Open an app from the home screen by name. It is categorised as a Execute tool in the Vphone MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Vphone MCP server in PolicyLayer and add a rule for open_app: 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 Vphone. Nothing to install.
open_app is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the open_app 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.
Set action: deny in the PolicyLayer policy for open_app. 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.
open_app is provided by the Vphone MCP server (pluginslab/vphone-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Vphone, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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17 Vphone tools catalogued and risk-classified — across an index of 43,000+ MCP servers.