extension_tool_userscripts_reset_world

THE RISK

Medium Risk

Why extension_tool_userscripts_reset_world needs a policy

Resetting a configuration to defaults is a reversible write operation — it overwrites current settings with default values. While it could disrupt active userscript behavior, the action can be reconfigured. It does not execute arbitrary code or irreversibly delete data, so Write is the most appropriate category.

From the tool's definition Reset USER_SCRIPT world configuration to defaults

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

POLICY

How to control extension_tool_userscripts_reset_world

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "extension_tool_userscripts_reset_world": {
      "limits": [
        {
          "counter": "extension_tool_userscripts_reset_world_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

extension_tool_userscripts_reset_world 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.

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

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EXPLORE

Related tools and policies

More WebMCP tools

Destructive extension_tool_userscripts_unregister Unregister userscripts by ID or filter Execute call_extension_tool Execute a browser extension tool. Use this to call extension tools that provide browser-le Execute call_website_tool Execute a tool from a website MCP server. Use this to call website-specific tools that you Execute extension_tool_userscripts_test_execute Test execute a script without registering it (Chrome 135+) Execute extension_tool_userscripts_configure_world Configure USER_SCRIPT world properties Execute extension_tool_userscripts_register Register a new userscript with Chrome userScripts API Write extension_tool_userscripts_update Update existing userscripts Read extension_tool_check_available_apis Check which Chrome Extension APIs are available to the extension

All 13 WebMCP tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about extension_tool_userscripts_reset_world

What does the extension_tool_userscripts_reset_world tool do? +

Reset USER_SCRIPT world configuration to defaults. It is categorised as a Write tool in the WebMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on extension_tool_userscripts_reset_world? +

Register the Web MCP server in PolicyLayer and add a rule for extension_tool_userscripts_reset_world: 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 WebMCP. Nothing to install.

What risk level is extension_tool_userscripts_reset_world? +

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

Can I rate-limit extension_tool_userscripts_reset_world? +

Yes. Add a rate_limit block to the extension_tool_userscripts_reset_world 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 extension_tool_userscripts_reset_world completely? +

Set action: deny in the PolicyLayer policy for extension_tool_userscripts_reset_world. 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 extension_tool_userscripts_reset_world? +

extension_tool_userscripts_reset_world is provided by the Web MCP server (miguelspizza/webmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every WebMCP tool call.

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

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