browser_trace_start

SERVERJshookmcp SOURCE@jshookmcp/jshook

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-vmoranv-jshookmcp/browser-trace-start.md

WHAT IT DOES

What browser_trace_start does on Jshookmcp

AI agents invoke browser_trace_start to trigger actions in Jshookmcp. 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.

RISK

Why browser_trace_start is rated High

Initiates browser automation with tracing capabilities; can extract sensitive data from active pages.

From the tool's definition begin a Chrome performance trace on the active page via page.tracing.start()

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs browser_trace_start safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Jshookmcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For browser_trace_start, this is the rule to start with:

browser_trace_start Rate-limited

browser_trace_start 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": {
    "browser_trace_start": {
      "limits": [
        {
          "counter": "browser_trace_start_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Jshookmcp, apply this rule, and every browser_trace_start call is checked against it from then on.

FAQ

Questions about browser_trace_start

What does the browser_trace_start tool do? +

Atomic primitive: begin a Chrome performance trace on the active page via page.tracing.start(). Pair with browser_trace_stop to save the trace to disk. Use a sensible categories list when you have a specific hypothesis (e.g. [. It is categorised as a Execute tool in the Jshookmcp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on browser_trace_start? +

Register the Jshook MCP server in PolicyLayer and add a rule for browser_trace_start: 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 Jshookmcp. Nothing to install.

What risk level is browser_trace_start? +

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

Can I rate-limit browser_trace_start? +

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

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

browser_trace_start is provided by the Jshook MCP server (@jshookmcp/jshook). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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