Scroll within an element or the active window using the canonical fallback chain: AX → CDP → coordinates. Scrolls until target text is visible, or by a fixed amount.
AI agents invoke scroll_with_fallback to trigger actions in ScreenHand. 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.
This tool performs a UI interaction (scrolling) via Accessibility APIs or Chrome DevTools Protocol, triggering external operations on the desktop/browser. It drives native UI actions rather than just reading state, placing it in the Execute category. Misuse could cause unintended navigation or UI state changes, but blast radius is moderate since scrolling alone is unlikely to cause irreversible harm.
From the tool's definition Scroll within an element or the active window using the canonical fallback chain: AX → CDP → coordinates. Scrolls until target text is visible, or by a fixed amount.
Documented attack patterns abuse exactly the kind of access scroll_with_fallback gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and ScreenHand, and nothing reaches the server without passing your rules. This is the rule we recommend for scroll_with_fallback:
{
"version": "1",
"default": "deny",
"tools": {
"scroll_with_fallback": {
"limits": [
{
"counter": "scroll_with_fallback_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}scroll_with_fallback 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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Scroll within an element or the active window using the canonical fallback chain: AX → CDP → coordinates. Scrolls until target text is visible, or by a fixed amount. It is categorised as a Execute tool in the ScreenHand MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the ScreenHand MCP server in PolicyLayer and add a rule for scroll_with_fallback: 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 ScreenHand. Nothing to install.
scroll_with_fallback 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 scroll_with_fallback 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 scroll_with_fallback. 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.
scroll_with_fallback is provided by the ScreenHand MCP server (manushi4/screenhand). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from ScreenHand, 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.
89 ScreenHand tools catalogued and risk-classified — across an index of 43,000+ MCP servers.