open_metro_bundler · MCP Connect MCP: Risk & Policy

WHAT IT DOES

What open_metro_bundler does on MCP Connect

AI agents invoke open_metro_bundler to trigger actions in MCP Connect. 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 open_metro_bundler needs a policy

Opening the Metro bundler involves starting or connecting to an external process/service. This is not a pure read operation; it triggers an external operation whose side effects depend on the environment (starting a dev server UI, potentially spawning processes). This fits Execute. Severity is medium as misuse could disrupt development environments or expose the bundler UI, but blast radius is limited.

From the tool's definition open_metro_bundler — 'Quick shortcut to open React Native Metro bundler UI' — triggers an external operation (launching/opening the Metro bundler UI)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

open_metro_bundler Rate-limited

open_metro_bundler 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": {
    "open_metro_bundler": {
      "limits": [
        {
          "counter": "open_metro_bundler_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 MCP Connect, so you can run agents against it safely.

FAQ

Questions about open_metro_bundler

What does the open_metro_bundler tool do? +

Quick shortcut to open React Native Metro bundler UI. It is categorised as a Execute tool in the MCP Connect MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on open_metro_bundler? +

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

What risk level is open_metro_bundler? +

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

Can I rate-limit open_metro_bundler? +

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

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

open_metro_bundler is provided by the MCP Connect MCP server (plaintest/mcp-connect). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.