mgba_run · mGBA MCP Server MCP: Risk & Policy

WHAT IT DOES

What mgba_run does on mGBA MCP Server

AI agents invoke mgba_run to trigger actions in mGBA MCP Server. 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 mgba_run needs a policy

mgba_run executes arbitrary ROM code within the emulator for a specified duration. While the immediate blast radius is limited to the emulated environment (Game Boy/GBA games cannot directly compromise the host system), the tool enables execution of attacker-controlled game code. Misuse could cause emulator crashes, infinite loops, or resource exhaustion.

From the tool's definition Tool description states 'Run a GB/GBC/GBA ROM for a specified number of frames' — actively executes emulated code. Sibling tools like mgba_run_lua and mgba_run_sequence further confirm this server is designed for code execution.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mgba_run Rate-limited

mgba_run 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": {
    "mgba_run": {
      "limits": [
        {
          "counter": "mgba_run_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 mGBA MCP Server, so you can run agents against it safely.

FAQ

Questions about mgba_run

What does the mgba_run tool do? +

Run a GB/GBC/GBA ROM for a specified number of frames and capture a screenshot. It is categorised as a Execute tool in the mGBA MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on mgba_run? +

Register the mGBA MCP Server MCP server in PolicyLayer and add a rule for mgba_run: 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 mGBA MCP Server. Nothing to install.

What risk level is mgba_run? +

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

Can I rate-limit mgba_run? +

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

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

mgba_run is provided by the mGBA MCP Server MCP server (struktured-labs/mgba-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.