browser_type · MCP Macaco Playwright MCP: Risk & Policy

WHAT IT DOES

What browser_type does on MCP Macaco Playwright

AI agents use browser_type to create or update resources in MCP Macaco Playwright — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP Macaco Playwright environment.

WHY IT NEEDS A POLICY

Why browser_type needs a policy

This tool creates or modifies data in web forms (Write category), which is reversible and can be undone by clearing or re-typing. It does not execute arbitrary code, delete data, or move money. Severity is medium because an AI agent could misuse this to inject malicious content into forms, modify sensitive fields, or interfere with legitimate user inputs, though the effects are generally reversible.

From the tool's definition Tool description explicitly states it 'Type text into editable element, replacing any existing content' — this modifies form fields and input elements reversibly through text entry.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_type Rate-limited

browser_type 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_type": {
      "limits": [
        {
          "counter": "browser_type_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 Macaco Playwright, so you can run agents against it safely.

FAQ

Questions about browser_type

What does the browser_type tool do? +

Type text into editable element, replacing any existing content (useful for clearing and filling inputs). It is categorised as a Write tool in the MCP Macaco Playwright 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_type? +

Register the MCP Macaco Playwright MCP server in PolicyLayer and add a rule for browser_type: 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 Macaco Playwright. Nothing to install.

What risk level is browser_type? +

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

Can I rate-limit browser_type? +

Yes. Add a rate_limit block to the browser_type 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_type completely? +

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

browser_type is provided by the MCP Macaco Playwright MCP server (macacoai/mcp-playwright). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.