AI agents call browser_perf to retrieve information from Termux Browser Pilot without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves performance metrics from the current page (e.g., load times, resource timings, FCP, LCP). It is a read-only operation with no side effects, no code execution, and no data modification. The blast radius of misuse is minimal—an agent could gather performance data but cannot interact with page content, modify state, or trigger actions.
From the tool's definition Tool name 'browser_perf' and description 'Get page performance metrics' indicate a retrieval operation that queries performance data without modifying browser state or triggering external actions.
Documented attack patterns abuse exactly the kind of access browser_perf gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Termux Browser Pilot, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_perf:
{
"version": "1",
"default": "deny",
"tools": {
"browser_perf": {}
}
}browser_perf is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get page performance metrics. It is categorised as a Read tool in the Termux Browser Pilot MCP Server, which means it retrieves data without modifying state.
Register the Termux Browser Pilot MCP server in PolicyLayer and add a rule for browser_perf: 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 Termux Browser Pilot. Nothing to install.
browser_perf is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the browser_perf 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.
Set action: deny in the PolicyLayer policy for browser_perf. 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.
browser_perf is provided by the Termux Browser Pilot MCP server (salviz/termux-browser-pilot). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Termux Browser Pilot, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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148 Termux Browser Pilot tools catalogued and risk-classified — across an index of 43,000+ MCP servers.