restart_browser · Nav MCP: Risk & Policy

WHAT IT DOES

What restart_browser does on Navmcp

AI agents invoke restart_browser to trigger actions in Navmcp. 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 restart_browser needs a policy

Restarting the browser is an Execute action because it triggers an external operation that controls system resources and browser state. While not destructive (data is not deleted) or financial, it is a trigger-based action that modifies application state.

From the tool's definition Tool is named 'restart_browser' and described as 'Restart the browser.' This explicitly triggers an external operation (browser process restart) whose effects are operational state changes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

restart_browser Rate-limited

restart_browser 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": {
    "restart_browser": {
      "limits": [
        {
          "counter": "restart_browser_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 Navmcp, so you can run agents against it safely.

FAQ

Questions about restart_browser

What does the restart_browser tool do? +

Restart the browser. It is categorised as a Execute tool in the Navmcp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on restart_browser? +

Register the Nav MCP server in PolicyLayer and add a rule for restart_browser: 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 Navmcp. Nothing to install.

What risk level is restart_browser? +

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

Can I rate-limit restart_browser? +

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

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

restart_browser is provided by the Nav MCP server (jianlins/navmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

// THE FULL RECORD

restart_browser is one line of Nav's registry record.

The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.

Teams ship this data inside their own products. See what a licence covers →