Emulate device viewport and UA via preset or custom.
AI agents invoke emulate_device to trigger actions in OpenChrome. 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 falls under Execute rather than Write because it doesn't persistently modify data; instead, it runs/triggers browser configuration changes whose effects depend on the arguments provided (choice of device preset or custom settings). The ability to spoof user agents and viewport sizes could be misused to bypass security checks, impersonate different clients, or trigger unintended application paths.
From the tool's definition The tool 'emulate_device' with description 'Emulate device viewport and UA via preset or custom' enables execution of browser manipulation actions (viewport changes, user agent spoofing) that alter the execution environment and can trigger different…
Documented attack patterns abuse exactly the kind of access emulate_device gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and OpenChrome, and nothing reaches the server without passing your rules. This is the rule we recommend for emulate_device:
{
"version": "1",
"default": "deny",
"tools": {
"emulate_device": {
"limits": [
{
"counter": "emulate_device_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}emulate_device 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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Emulate device viewport and UA via preset or custom. It is categorised as a Execute tool in the OpenChrome MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the OpenChrome MCP server in PolicyLayer and add a rule for emulate_device: 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 OpenChrome. Nothing to install.
emulate_device 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 emulate_device 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 emulate_device. 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.
emulate_device is provided by the OpenChrome MCP server (shaun0927/openchrome). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 106 OpenChrome tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
106 OpenChrome tools catalogued and risk-classified — across an index of 42,500+ MCP servers.