AI agents invoke browser_hover to trigger actions in Fast Playwright MCP. 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.
Hovering is a browser interaction that can trigger JavaScript events (mouseover, mouseenter, etc.), potentially causing UI state changes, popups, or dynamic content loading. It is an external operation whose effects depend on the target element, making it Execute. The blast radius is low since hover typically has minimal irreversible side effects.
From the tool's definition Hover over element on page — triggers a browser action (mouse hover) on a live page
Documented attack patterns abuse exactly the kind of access browser_hover gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Fast Playwright MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for browser_hover:
{
"version": "1",
"default": "deny",
"tools": {
"browser_hover": {
"limits": [
{
"counter": "browser_hover_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}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.
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Hover over element on page. It is categorised as a Execute tool in the Fast Playwright MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Fast Playwright 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 Fast Playwright MCP. Nothing to install.
browser_hover is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
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.
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.
browser_hover is provided by the Fast Playwright MCP server (tontoko/fast-playwright-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 34 Fast Playwright MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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34 Fast Playwright MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.