browser_hover · Browser MCP: Risk & Policy

WHAT IT DOES

What browser_hover does on Browser

AI agents invoke browser_hover to trigger actions in Browser. 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 browser_hover needs a policy

Hovering over an element is a browser automation action that can trigger side effects such as JavaScript event handlers (mouseover, mouseenter), tooltips, dropdown menus, or other dynamic UI changes. It is an external operation whose effects depend on the target element, placing it in the Execute category. The blast radius is low since hovering alone rarely causes destructive or irreversible changes.

From the tool's definition Hover over an element — triggers browser interaction/action on a target element

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

browser_hover Rate-limited

browser_hover 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": {
    "browser_hover": {
      "limits": [
        {
          "counter": "browser_hover_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 Browser, so you can run agents against it safely.

FAQ

Questions about browser_hover

What does the browser_hover tool do? +

Hover over an element (see browser_docs). It is categorised as a Execute tool in the Browser 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_hover? +

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

What risk level is browser_hover? +

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

Can I rate-limit browser_hover? +

Yes. Add a rate_limit block to the browser_hover 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_hover completely? +

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

browser_hover is provided by the Browser MCP server (ricardodeazambuja/browser-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.