AI agents call browser_cookie_get 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.
This tool retrieves cookie data from a browser context without modifying it, which is a Read operation. However, cookies often contain sensitive authentication tokens and session identifiers; exfiltration of cookies could enable session hijacking or unauthorized access. Severity is medium-to-high depending on cookie contents, but the tool itself is non-destructive and read-only.
From the tool's definition Tool name 'browser_cookie_get' and sibling context (browser_cookie_list, browser_cookie_set, browser_cookie_delete, browser_cookie_clear) indicate this retrieves cookie data.
Documented attack patterns abuse exactly the kind of access browser_cookie_get 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_get:
{
"version": "1",
"default": "deny",
"tools": {
"browser_cookie_get": {}
}
}browser_cookie_get 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_get. 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_get: 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_get 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_get 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_get. 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_get 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.