Create a new isolated browser session. Each session runs an independent MCP backend process.
AI agents invoke create_session to trigger actions in Playwright Parallel. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Creating a browser session launches an independent backend process, which constitutes executing an external operation. While it doesn't directly run user code or shell commands, spawning a new process with browser automation capabilities has a high blast radius — it enables subsequent browsing, data exfiltration, or further automation actions. The most severe applicable category is Execute.
From the tool's definition Create a new isolated browser session. Each session runs an independent MCP backend process.
Documented attack patterns abuse exactly the kind of access create_session gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Playwright Parallel, and nothing reaches the server without passing your rules. This is the rule we recommend for create_session:
{
"version": "1",
"default": "deny",
"tools": {
"create_session": {
"limits": [
{
"counter": "create_session_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}create_session stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Create a new isolated browser session. Each session runs an independent MCP backend process. It is categorised as a Execute tool in the Playwright Parallel MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Playwright Parallel MCP server in PolicyLayer and add a rule for create_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 Playwright Parallel. Nothing to install.
create_session is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the create_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 create_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.
create_session is provided by the Playwright Parallel MCP server (sumyapp/playwright-parallel-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Playwright Parallel, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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3 Playwright Parallel tools catalogued and risk-classified — across an index of 43,000+ MCP servers.