chrome

Overview Schema Source Related Servers Discussions Admin

Emulate device/network

emulate

Override browser viewport, device scale, mobile mode, user agent, geolocation, color scheme, timezone, and network conditions to test pages under simulated environments; reset overrides when done.

Instructions

Emulate viewport size, device scale, mobile, user agent, geolocation, color scheme, timezone or offline/network conditions. Requires CDP. Use action="reset" to clear overrides.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "emulate"
  }
}

Input Schema

Name	Required	Default
`tabId`	No
`width`	No
`action`	No	set
`height`	No
`mobile`	No
`latency`	No
`offline`	No
`accuracy`	No
`latitude`	No
`timezone`	No
`longitude`	No
`userAgent`	No
`colorScheme`	No
`uploadThroughput`	No
`deviceScaleFactor`	No
`downloadThroughput`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.3Nov 9, 2026

TDQS

A3.7/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full behavioral burden. It usefully discloses that CDP is required and that reset clears overrides, but says nothing about whether overrides persist across navigations, how partial sets behave, or what the tool returns. Adequate but with real gaps for a state-mutating tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences, front-loaded with the emulation scope and ending with the reset escape hatch. No filler and every clause carries information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 16-parameter, annotation-free, no-output-schema mutation tool, the description covers the conceptual parameter surface but leaves behavioral details (persistence, return values, error modes) and several parameters (tabId, default action) unaddressed. It is a usable but not complete brief.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% across 16 parameters, so the description must compensate. It names most emulation axes (viewport size, device scale, mobile, user agent, geolocation, color scheme, timezone, network conditions), which maps conceptually onto width/height, deviceScaleFactor, userAgent, lat/long/accuracy, colorScheme, timezone, offline/latency/throughput. However, it omits the default action="set", tabId, and any units or formats for numeric fields like latency and throughput.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb (emulate) and enumerates the exact resources it affects: viewport size, device scale, mobile, user agent, geolocation, color scheme, timezone, and network conditions. The purpose is unambiguous, though it does not explicitly differentiate itself from siblings like network or screenshot.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives a prerequisite ("Requires CDP") and a concrete operational instruction ("Use action=\"reset\" to clear overrides"), which tells the agent how to undo state. It stops short of naming when-not-to-use cases or alternative tools, so it is clear context without full routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server