AI agents call browser_cookie_list to retrieve information from Playwright without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Cookie listing is a read operation that retrieves data with no side effects. However, cookies often contain authentication tokens, session IDs, and sensitive user data, making unauthorized access a medium-severity risk if an AI agent were to exfiltrate or analyze them without authorization. The tool itself performs no destructive or write action.
From the tool's definition Tool name 'browser_cookie_list' and sibling tools like 'browser_cookie_get', 'browser_cookie_clear', 'browser_cookie_delete', 'browser_cookie_set' indicate this retrieves browser cookies without modifying them. The 'list' suffix confirms read-only enumeration.
Documented attack patterns abuse exactly the kind of access browser_cookie_list gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Playwright, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_cookie_list:
{
"version": "1",
"default": "deny",
"tools": {
"browser_cookie_list": {}
}
}browser_cookie_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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browser_cookie_list. It is categorised as a Read tool in the Playwright MCP Server, which means it retrieves data without modifying state.
Register the Playwright MCP server in PolicyLayer and add a rule for browser_cookie_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 Playwright. Nothing to install.
browser_cookie_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_cookie_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_cookie_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_cookie_list is provided by the Playwright MCP server (@playwright/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Playwright, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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68 Playwright tools catalogued and risk-classified — across an index of 43,000+ MCP servers.