l3_performance_budget · Lighthouse MCP: Risk & Policy

WHAT IT DOES

What l3_performance_budget does on Lighthouse MCP

AI agents invoke l3_performance_budget to trigger actions in Lighthouse 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 l3_performance_budget needs a policy

l3_performance_budget triggers real processes with real consequences. An agent gone sideways doesn't fire it once — it starts dozens of builds, sends mass notifications, or burns through compute before anyone looks up.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

l3_performance_budget Rate-limited

l3_performance_budget 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": {
    "l3_performance_budget": {
      "limits": [
        {
          "counter": "l3_performance_budget_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 Lighthouse MCP, so you can run agents against it safely.

FAQ

Questions about l3_performance_budget

What does the l3_performance_budget tool do? +

Layer 3 - Analyze site performance against defined budgets and provide strategic recommendations. It is categorised as a Execute tool in the Lighthouse 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 l3_performance_budget? +

Register the Lighthouse MCP server in PolicyLayer and add a rule for l3_performance_budget: 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 Lighthouse MCP. Nothing to install.

What risk level is l3_performance_budget? +

l3_performance_budget is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit l3_performance_budget? +

Yes. Add a rate_limit block to the l3_performance_budget 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 l3_performance_budget completely? +

Set action: deny in the PolicyLayer policy for l3_performance_budget. 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 l3_performance_budget? +

l3_performance_budget is provided by the Lighthouse MCP server (mizchi/lighthouse-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.