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browser_highlight

browser_highlight

How to control browser_highlight ↓

What browser_highlight does on Playwright

AI agents invoke browser_highlight to trigger actions in Playwright. 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.

High Risk

Why browser_highlight needs a policy

Playwright is a browser automation framework. 'browser_highlight' likely triggers a visual highlighting action in the browser (e.g., highlighting an element), which constitutes a browser action/Execute category. However, with no description, confidence is low.

From the tool's definition Tool name 'browser_highlight' on a Playwright server; no description provided.

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

How to control browser_highlight

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

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "browser_highlight": {
      "limits": [
        {
          "counter": "browser_highlight_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

browser_highlight 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.

  1. Create a free account and register Playwright — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
RATE-LIMIT THIS TOOL →

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Related tools and policies

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Questions about browser_highlight

What does the browser_highlight tool do? +

browser_highlight. It is categorised as a Execute tool in the Playwright 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_highlight? +

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

What risk level is browser_highlight? +

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

Can I rate-limit browser_highlight? +

Yes. Add a rate_limit block to the browser_highlight 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_highlight completely? +

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

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

Enforce policy on every Playwright tool call.

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

Free to start. No card required.

68 Playwright tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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