open_browser · Selenium MCP Server MCP: Risk & Policy

WHAT IT DOES

What open_browser does on Selenium MCP Server

AI agents invoke open_browser to trigger actions in Selenium MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why open_browser needs a policy

Opening a browser initiates an external process and enables subsequent browser control operations. While the tool itself launches a browser instance, it is the gateway to all further browser automation actions.

From the tool's definition Tool name 'open_browser' on a Selenium WebDriver MCP server described as enabling AI agents to 'control real browsers for automation tasks like navigation, element interaction, and screenshot capture'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

open_browser Rate-limited

open_browser 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.

View as policy code

policy.json

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

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about open_browser

What does the open_browser tool do? +

open_browser. It is categorised as a Execute tool in the Selenium MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on open_browser? +

Register the Selenium MCP Server MCP server in PolicyLayer and add a rule for open_browser: 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 Selenium MCP Server. Nothing to install.

What risk level is open_browser? +

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

Can I rate-limit open_browser? +

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

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

open_browser is provided by the Selenium MCP Server MCP server (nayakprashant/selenium-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.