arc_focus_space · Arc Browser MCP: Risk & Policy

WHAT IT DOES

What arc_focus_space does on Arc Browser MCP

AI agents invoke arc_focus_space to trigger actions in Arc Browser MCP. 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 arc_focus_space needs a policy

Focusing a space triggers an external operation that changes the visible state of the Arc Browser UI. It is not a simple read, nor does it create/modify data reversibly in the traditional sense — it controls the browser's displayed state. 'Changes visible Arc state' confirms a side effect, placing it in Execute.

From the tool's definition Focus an Arc Space by explicit id. This changes visible Arc state.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

arc_focus_space Rate-limited

arc_focus_space 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": {
    "arc_focus_space": {
      "limits": [
        {
          "counter": "arc_focus_space_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 Arc Browser MCP, so you can run agents against it safely.

FAQ

Questions about arc_focus_space

What does the arc_focus_space tool do? +

Focus an Arc Space by explicit id. This changes visible Arc state. It is categorised as a Execute tool in the Arc Browser MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on arc_focus_space? +

Register the Arc Browser MCP server in PolicyLayer and add a rule for arc_focus_space: 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_focus_space? +

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

Can I rate-limit arc_focus_space? +

Yes. Add a rate_limit block to the arc_focus_space 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_focus_space completely? +

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

arc_focus_space 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.