nodriver-mcp-server

Overview Schema Source Related Servers Discussions Admin

Emulate page conditions

emulate

Idempotent

Override network, CPU, geolocation, user agent, color scheme, or viewport on a page to test under varied conditions. Each setting is independent and persists across navigations until reset.

Instructions

Emulate network, CPU, geolocation, user agent, color scheme or viewport.

Applies to the selected page and persists across navigations until reset_emulation. Every parameter is independent — pass only what you want to change, leave the rest at their defaults. Settings already in force are carried over rather than dropped: a user_agent on its own keeps the client hints a device preset established, and a viewport on its own keeps its touch and mobile flags unless you clear them with notouch / nomobile.

To emulate a real phone or tablet, use emulate_device instead: it sets user agent, client hints, viewport, DPR and touch as one coherent set, which hand-assembled overrides here get wrong in ways anti-bot systems detect.

Turning touch on in the viewport also changes how click behaves — CDP mouse input can crash a touch-emulated renderer, so clicks fall back to the scripted path (isTrusted=false) for as long as touch is enabled.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`browser`	No	Which browser to act on. Each name is an independent Chrome, created on first use. Omit for the shared default; parallel agents each need their own name.	default
`viewport`	No	Viewport override as "WIDTHxHEIGHTxDPR[,mobile][,touch][,landscape]", e.g. "375x812x3,mobile,touch" or "1920x1080x1". The trailing flags are optional: `mobile` turns on mobile viewport behaviour, `touch` enables touch emulation, `landscape` sets the screen orientation. Omitting `mobile` or `touch` leaves that setting as it is, so resizing after emulate_device keeps the phone's touch support; turn them off explicitly with `nomobile` / `notouch`. Empty string leaves the viewport unchanged.
`user_agent`	No	Override the User-Agent header and navigator.userAgent. Omit to leave unchanged; pass an empty string to restore Chrome's real one. This does NOT touch UA client hints (Sec-CH-UA-*), which then contradict the spoofed UA and give the automation away — use emulate_device for mobile, it sets both consistently.
`geolocation`	No	Override geolocation, as "latitude,longitude" (e.g. "37.7749,-122.4194"). Omit to leave unchanged; pass an empty string to clear a previous override.
`color_scheme`	No	Emulate the prefers-color-scheme media feature. "auto" clears a previous override; empty string leaves it unchanged.
`network_conditions`	No	Throttle the network to a preset profile. "Offline" cuts the connection entirely. Empty string leaves throttling unchanged.
`cpu_throttling_rate`	No	Slow the CPU by this factor to emulate a low-end device (4 = 4x slower; 1-20 is the useful range). 0 or 1 means no throttling.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv2.5.0Sep 25, 2026

addedInput schema / properties / browser

Added value: +{
+  "default": "default",
+  "description": "Which browser to act on. Each name is an independent Chrome, created on first use. Omit for the shared default; parallel agents each need their own name.",
+  "type": "string"
+}

changedInput schema / properties / viewport / description

Previous value: -"Viewport override as \"WIDTHxHEIGHTxDPR[,mobile][,touch][,landscape]\", e.g. \"375x812x3,mobile,touch\" or \"1920x1080x1\". The trailing flags are optional: `mobile` turns on mobile viewport behaviour, `touch` enables touch emulation, `landscape` sets the screen orientation. Empty string leaves the viewport unchanged."New value: +"Viewport override as \"WIDTHxHEIGHTxDPR[,mobile][,touch][,landscape]\", e.g. \"375x812x3,mobile,touch\" or \"1920x1080x1\". The trailing flags are optional: `mobile` turns on mobile viewport behaviour, `touch` enables touch emulation, `landscape` sets the screen orientation. Omitting `mobile` or `touch` leaves that setting as it is, so resizing after emulate_device keeps the phone's touch support; turn them off explicitly with `nomobile` / `notouch`. Empty string leaves the viewport unchanged."

First observedv1.7.2Aug 7, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Beyond the annotations, the description discloses important behavioral traits: settings persist across navigations, already-applied settings are carried over rather than dropped, and enabling touch changes click behavior to a scripted path with isTrusted=false. It also warns about client-hint contradictions that can reveal automation. This is rich, non-obvious context that annotations alone do not provide.

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?

The description is well-structured and front-loaded with the core purpose, followed by scope, parameter behavior, sibling distinction, and a critical side-effect warning. Every paragraph earns its place, and nothing is redundant with the schema.

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

Completeness5/5

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

For a tool with 7 optional parameters, full schema coverage, an output schema, and clear annotations, the description is complete. It covers persistence, cross-parameter interactions, how to clear overrides, when to prefer emulate_device, and a dangerous interaction with click behavior. An agent has what it needs to select and invoke the tool correctly.

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

Parameters4/5

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

The input schema already covers all 7 parameters with 100% coverage, so the baseline is 3. The description adds meaningful cross-parameter semantics: every parameter is independent, pass only what you want to change, settings in force are carried over, and empty strings or notouch/nomobile clear/disable overrides. This goes beyond the individual schema descriptions.

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

Purpose5/5

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

The description opens with a specific verb and resource: 'Emulate network, CPU, geolocation, user agent, color scheme or viewport.' It clearly distinguishes the tool from siblings by naming emulate_device and reset_emulation as the related alternatives, so an agent knows exactly what this tool does and what it does not do.

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

Usage Guidelines5/5

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

The description explicitly states when to use this tool versus emulate_device: for real phone/tablet emulation, use emulate_device because it sets a coherent set of overrides. It also explains persistence until reset_emulation and emphasizes the independence of parameters, giving an agent clear conditions for invocation.

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

Deploy Server