runPerformanceAudit · BrowserTools MCP: Risk & Policy

WHAT IT DOES

What runPerformanceAudit does on BrowserTools MCP

AI agents invoke runPerformanceAudit to trigger actions in BrowserTools 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 runPerformanceAudit needs a policy

This tool executes an audit process on the currently loaded browser page, causing external operations to be performed (analyzing page performance). It is not merely reading static data but actively triggering a scan/audit action. It does not modify or delete data, so Execute is the appropriate category. Misuse could cause performance degradation or expose sensitive page data, warranting medium severity.

From the tool's definition 'Run a performance audit on the current page' — actively triggers an audit operation against the live browser page

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

runPerformanceAudit Rate-limited

runPerformanceAudit 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": {
    "runPerformanceAudit": {
      "limits": [
        {
          "counter": "runperformanceaudit_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 BrowserTools MCP, so you can run agents against it safely.

FAQ

Questions about runPerformanceAudit

What does the runPerformanceAudit tool do? +

Run a performance audit on the current page. It is categorised as a Execute tool in the BrowserTools 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 runPerformanceAudit? +

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

What risk level is runPerformanceAudit? +

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

Can I rate-limit runPerformanceAudit? +

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

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

runPerformanceAudit is provided by the BrowserTools MCP server (sugatraj/cursor-browser-tools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.