browser.import_storage_state · MCP Playwright Browser MCP

WHAT IT DOES

What browser.import_storage_state does on MCP Playwright Browser

AI agents use browser.import_storage_state to create or update resources in MCP Playwright Browser — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP Playwright Browser environment.

WHY IT NEEDS A POLICY

Why browser.import_storage_state needs a policy

This tool writes/injects storage state (cookies, tokens, session data) into a new browser context. It is reversible in principle (the context can be closed), so it falls under Write rather than Destructive. However, severity is high because importing arbitrary storage state can hijack authenticated sessions, impersonate users, or bypass security controls, giving an AI agent broad access to web applications.

From the tool's definition 'Import storage state by creating and selecting a new browser context' — injects authentication/session state (cookies, localStorage, etc.) into a browser context

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser.import_storage_state Rate-limited

browser.import_storage_state stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "browser.import_storage_state": {
      "limits": [
        {
          "counter": "browser.import_storage_state_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches MCP Playwright Browser, so you can run agents against it safely.

FAQ

Questions about browser.import_storage_state

What does the browser.import_storage_state tool do? +

Import storage state by creating and selecting a new browser context. It is categorised as a Write tool in the MCP Playwright Browser MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on browser.import_storage_state? +

Register the MCP Playwright Browser MCP server in PolicyLayer and add a rule for browser.import_storage_state: 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 Browser. Nothing to install.

What risk level is browser.import_storage_state? +

browser.import_storage_state is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit browser.import_storage_state? +

Yes. Add a rate_limit block to the browser.import_storage_state 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.

How do I block browser.import_storage_state completely? +

Set action: deny in the PolicyLayer policy for browser.import_storage_state. 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.

What MCP server provides browser.import_storage_state? +

browser.import_storage_state is provided by the MCP Playwright Browser MCP server (mhrnqaruni/mcp-playwright-browser). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.