AI agents invoke validate_app 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.
This tool runs an external tool (altool) to perform validation checks on an app binary. It triggers an external operation/process execution rather than simply reading data or writing/modifying files. It doesn't move money, delete data, or create/modify project files — it executes a validation process against Apple's submission infrastructure.
From the tool's definition Validate an app for App Store submission using altool
Documented attack patterns abuse exactly the kind of access validate_app gives an agent:
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 validate_app:
{
"version": "1",
"default": "deny",
"tools": {
"validate_app": {
"limits": [
{
"counter": "validate_app_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}validate_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.
Free to start. No card required.
Validate an app for App Store submission using altool. 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.
Register the Xcode MCP server in PolicyLayer and add a rule for validate_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 Xcode. Nothing to install.
validate_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 validate_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 validate_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.
validate_app 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.
Deterministic rules across all 69 Xcode tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
69 Xcode tools catalogued and risk-classified — across an index of 42,500+ MCP servers.