AI agents call close_browser_session to permanently remove resources in Mcp Playwright — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Closing a browser session is irreversible — it terminates the session and destroys any associated state, cookies, and unsaved data. This cannot be undone, matching the Destructive category. Severity is medium since it disrupts ongoing automation workflows and loses session state, but has limited broader system impact.
From the tool's definition 关闭当前浏览器会话 (Close current browser session)
Documented attack patterns abuse exactly the kind of access close_browser_session gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mcp Playwright, and nothing reaches the server without passing your rules. This is the rule we recommend for close_browser_session:
{
"version": "1",
"default": "deny",
"hide": [
"close_browser_session"
]
}close_browser_session disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
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关闭当前浏览器会话. It is categorised as a Destructive tool in the Mcp Playwright MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Mcp Playwright MCP server in PolicyLayer and add a rule for close_browser_session: 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 Mcp Playwright. Nothing to install.
close_browser_session is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the close_browser_session 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 close_browser_session. 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.
close_browser_session is provided by the Mcp Playwright MCP server (ma-pony/mcp-playwright). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Mcp Playwright, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
12 Mcp Playwright tools catalogued and risk-classified — across an index of 43,000+ MCP servers.