AI agents call browser_css_list 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 information about existing stylesheets without creating, modifying, deleting, or executing anything. It is a read-only operation that queries the state of injected CSS. The blast radius if misused is minimal—an AI agent could only enumerate stylesheet information, which poses no security or operational risk.
From the tool's definition Tool name contains 'list' and description states 'List all injected custom stylesheets' — a query operation with no modification or side effects.
Documented attack patterns abuse exactly the kind of access browser_css_list 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_css_list:
{
"version": "1",
"default": "deny",
"tools": {
"browser_css_list": {}
}
}browser_css_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all injected custom stylesheets. 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_css_list: 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_css_list 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_css_list 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_css_list. 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_css_list 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.