browser_save_storage_state · MCP: Risk & Policy

WHAT IT DOES

What browser_save_storage_state does on Mcp

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

WHY IT NEEDS A POLICY

Why browser_save_storage_state needs a policy

The tool creates or modifies a JSON artifact file by persisting storage state. This is a reversible Write operation—the file can be edited or deleted. It does not execute arbitrary code, delete data irreversibly, move money, or perform external operations with unpredictable effects.

From the tool's definition Tool name contains 'save' and description states 'Persist the current Playwright storage state to a runtime artifact JSON file.' This writes data to a file.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_save_storage_state Rate-limited

browser_save_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_save_storage_state": {
      "limits": [
        {
          "counter": "browser_save_storage_state_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

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

FAQ

Questions about browser_save_storage_state

What does the browser_save_storage_state tool do? +

Persist the current Playwright storage state to a runtime artifact JSON file. It is categorised as a Write tool in the Mcp 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_save_storage_state? +

Register the MCP server in PolicyLayer and add a rule for browser_save_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. Nothing to install.

What risk level is browser_save_storage_state? +

browser_save_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_save_storage_state? +

Yes. Add a rate_limit block to the browser_save_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_save_storage_state completely? +

Set action: deny in the PolicyLayer policy for browser_save_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_save_storage_state? +

browser_save_storage_state is provided by the MCP server (victormyschik/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

// THE FULL RECORD

browser_save_storage_state is one line of 's registry record.

The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.

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