AI agents call list_sessions to retrieve information from Playwright Parallel 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 active browser sessions without modifying, deleting, or executing any operations. It is a read-only query operation with minimal blast radius if misused by an AI agent—at most, an agent could gain visibility into session metadata, but cannot affect browser state or data.
From the tool's definition Tool name 'list_sessions' and description 'List all active browser sessions' indicate a query/retrieval operation with no side effects. The verb 'list' is explicitly enumerated in the Read category examples.
Documented attack patterns abuse exactly the kind of access list_sessions 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 list_sessions:
{
"version": "1",
"default": "deny",
"tools": {
"list_sessions": {}
}
}list_sessions 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 active browser sessions. It is categorised as a Read tool in the Playwright Parallel MCP Server, which means it retrieves data without modifying state.
Register the Playwright Parallel MCP server in PolicyLayer and add a rule for list_sessions: 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.
list_sessions 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 list_sessions 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 list_sessions. 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.
list_sessions 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.