browser_close

THE RISK

High Risk

Why browser_close needs a policy

This tool terminates a browser session and releases associated resources. It is an operational action (closing a process/session) rather than a pure read, data write, or destructive data action. It fits Execute as it triggers an external operation (terminating the browser process). Severity is low since misuse would only prematurely end a browser session, not cause data loss or financial harm.

From the tool's definition 'Close the interactive browser session and free resources'

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

POLICY

How to control browser_close

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "browser_close": {
      "limits": [
        {
          "counter": "browser_close_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

browser_close stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

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

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Web Scraper tools

Destructive clear_cache Clear the response cache. Use when cached data may be stale. Destructive clear_history Clear scraping history. Destructive clear_host_profile Delete one host profile record from the profile store. Destructive clear_session Clear a browser session (cookies, storage). Use for fresh starts. Execute cancel_job Cancel a running async job. Execute browser_evaluate Run a JavaScript expression on the current page and return the result. Execute browser_navigate Navigate the interactive browser to a URL. Execute browser_solve_challenge Explicitly trigger challenge detection and solving on the current page.

All 62 Web Scraper tools →

Execute tools on other servers

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Go deeper

High-risk tools in Web Scraper → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about browser_close

What does the browser_close tool do? +

Close the interactive browser session and free resources. It is categorised as a Execute tool in the Web Scraper MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on browser_close? +

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

What risk level is browser_close? +

browser_close is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit browser_close? +

Yes. Add a rate_limit block to the browser_close 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_close completely? +

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

browser_close is provided by the Web Scraper MCP server (imyourboyroy/webscrapertoolkit). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Web Scraper tool call.

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

CHECK YOUR STACK →