browser_close_session · MCP: Risk & Policy

WHAT IT DOES

What browser_close_session does on Mcp

AI agents use browser_close_session 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_close_session needs a policy

An AI agent can call browser_close_session faster than any human can review — one bad instruction and it creates or modifies resources in Mcp by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_close_session Rate-limited

browser_close_session 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_close_session": {
      "limits": [
        {
          "counter": "browser_close_session_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, so you can run agents against it safely.

FAQ

Questions about browser_close_session

What does the browser_close_session tool do? +

Close a browser session and release Chromium resources. 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_close_session? +

Register the MCP server in PolicyLayer and add a rule for browser_close_session: 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_close_session? +

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

Can I rate-limit browser_close_session? +

Yes. Add a rate_limit block to the browser_close_session 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_session completely? +

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

browser_close_session 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.