arc_create_tab · Arc Browser MCP: Risk & Policy

WHAT IT DOES

What arc_create_tab does on Arc Browser MCP

AI agents use arc_create_tab to create or update resources in Arc Browser MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Arc Browser MCP environment.

WHY IT NEEDS A POLICY

Why arc_create_tab needs a policy

arc_create_tab performs a creation operation that modifies browser state by adding a new tab to a specified Space. This is Write-category behavior (reversible creation/modification). Severity is medium because misuse could clutter the browser with unwanted tabs or interfere with user workflows, but the effect is easily undone by closing the tab.

From the tool's definition Tool description states 'Create a new Arc tab' — creates a new resource (tab) in Arc Browser. This is a reversible modification of browser state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

arc_create_tab Rate-limited

arc_create_tab stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "arc_create_tab": {
      "limits": [
        {
          "counter": "arc_create_tab_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Arc Browser MCP, so you can run agents against it safely.

FAQ

Questions about arc_create_tab

What does the arc_create_tab tool do? +

Create a new Arc tab in an explicit Space and return its verified tab id. It is categorised as a Write tool in the Arc Browser MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on arc_create_tab? +

Register the Arc Browser MCP server in PolicyLayer and add a rule for arc_create_tab: 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 Arc Browser MCP. Nothing to install.

What risk level is arc_create_tab? +

arc_create_tab is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit arc_create_tab? +

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

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

arc_create_tab is provided by the Arc Browser MCP server (jasoncronje/arc-browser-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.