Check if a ROM is currently loaded in the emulator
AI agents call is_rom_loaded to retrieve information from MCP GameBoy Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only reads the state of the emulator to determine whether a ROM is loaded. It has no side effects, does not modify data, and does not execute code or commands. It is a simple status check, making it a Read category tool with low severity since misuse poses no harm to the system or data.
From the tool's definition Tool description states 'Check if a ROM is currently loaded in the emulator' — this is a query operation that retrieves the current state of the emulator without modifying anything.
Documented attack patterns abuse exactly the kind of access is_rom_loaded gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP GameBoy Server, and nothing reaches the server without passing your rules. This is the rule we recommend for is_rom_loaded:
{
"version": "1",
"default": "deny",
"tools": {
"is_rom_loaded": {}
}
}is_rom_loaded is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Check if a ROM is currently loaded in the emulator. It is categorised as a Read tool in the MCP GameBoy Server MCP Server, which means it retrieves data without modifying state.
Register the MCP GameBoy Server MCP server in PolicyLayer and add a rule for is_rom_loaded: 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 MCP GameBoy Server. Nothing to install.
is_rom_loaded is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the is_rom_loaded 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 is_rom_loaded. 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.
is_rom_loaded is provided by the MCP GameBoy Server MCP server (mario-andreschak/mcp-gameboy). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP GameBoy Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
5 MCP GameBoy Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.