save_session_state

THE RISK

Low Risk

Why save_session_state needs a policy

The tool reads and captures existing browser session data (cookies, localStorage, sessionStorage) into an in-memory snapshot. It does not modify, delete, or transmit any data externally — it is a read/capture operation for reverse engineering analysis. The snapshot is in-memory and scoped to the current session.

From the tool's definition Save current page session state (cookies/localStorage/sessionStorage) into in-memory snapshot

Documented attack patterns abuse exactly the kind of access save_session_state gives an agent:

POLICY

How to control save_session_state

PolicyLayer is an MCP gateway — it sits between your AI agents and JS Reverse Strong MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for save_session_state:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "save_session_state": {}
  }
}

save_session_state is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register JS Reverse Strong MCP — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

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EXPLORE

Related tools and policies

More JS Reverse Strong MCP tools

Destructive delete_session_state Delete one in-memory session snapshot by sessionId. Destructive remove_hook Remove a hook by id. Execute evaluate_on_callframe Evaluates a JavaScript expression in the context of a specific call frame while paused. Th Execute inject_preload_script Register a JavaScript snippet that will run on future document loads before page scripts e Execute navigate_page Navigates the currently selected page to a URL, or performs back/forward/reload navigation Execute new_page Creates a new page and navigates to the specified URL. Waits for DOMContentLoaded event (n Execute stop_monitor Stops an event monitor. Execute wait_for_element Wait for selector to appear.

All 85 JS Reverse Strong MCP tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about save_session_state

What does the save_session_state tool do? +

Save current page session state (cookies/localStorage/sessionStorage) into in-memory snapshot. It is categorised as a Read tool in the JS Reverse Strong MCP MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on save_session_state? +

Register the JS Reverse Strong MCP server in PolicyLayer and add a rule for save_session_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 JS Reverse Strong MCP. Nothing to install.

What risk level is save_session_state? +

save_session_state is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit save_session_state? +

Yes. Add a rate_limit block to the save_session_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 save_session_state completely? +

Set action: deny in the PolicyLayer policy for save_session_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 save_session_state? +

save_session_state is provided by the JS Reverse Strong MCP server (lwjjike/jsreverser-strong-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every JS Reverse Strong MCP tool call.

Start from JS Reverse Strong MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →