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nodriver-mcp-server

nodriver-mcp-server

by andresolbach
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Local

Set browser launch flags

set_browser_flags
Destructive

Change Chrome launch flags at runtime and view current settings. Apply flags to control translate, extensions, extra arguments, and startup mode; restart Chrome to make changes take effect.

Instructions

Change Chrome's launch flags at runtime, and show the current ones.

Call with no arguments at all to just read the effective configuration — that form changes nothing.

These are launch-time flags, so applying them restarts Chrome and closes every open page; on an ephemeral profile that also drops its cookies. Values set here override the NODRIVER_ENABLE_* environment variables.

Startup mode is saved per persistent profile: new_tab, urls or restore. With restart=False, current tabs stay open and the saved choice applies next time. Unlike the other flags, this choice survives MCP server restarts. Saved MCP startup choices take precedence over Chrome's startup setting.

Input Schema

NameRequiredDescriptionDefault
browserNoWhich 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
restartNoRestart Chrome now so the flags take effect, closing all open pages. Default true; false defers them to the next browser start.
translateNoTrue allows Chrome's Google Translate popup, false suppresses it. Omit to leave unchanged. Suppressed by default, because the popup covers page content and swallows clicks.
extensionsNoTrue allows externally-installed Chrome extensions, false blocks them. Omit to leave unchanged. Blocked by default, so no "an extension requires your attention" prompt appears. manage_extensions offers the same switch plus listing and loading.
extra_argsNoReplace the set of extra Chrome launch flags with this list, e.g. ["--lang=de-DE", "--window-size=1280,800"]. A leading "--" is added if missing. Pass [] to clear them, omit to leave unchanged. This replaces the list rather than appending to it.
startup_modeNoSave this persistent profile's startup mode: new_tab (default), urls (open startup_urls), or restore (resume the last open tabs automatically). Select a persistent profile with use_profile first. Omit to leave unchanged. The choice survives MCP restarts; restart=False applies it on the next launch.
startup_urlsNoOne or more absolute HTTP(S) URLs, required with startup_mode='urls'. Only valid together with that mode.

Output Schema

NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changedv2.6.0
    • addedInput schema / properties / startup_mode
      Added value: +{
+  "anyOf": [
+    {
+      "enum": [
+        "new_tab",
+        "urls",
+        "restore"
+      ],
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Save this persistent profile's startup mode: new_tab (default), urls (open startup_urls), or restore (resume the last open tabs automatically). Select a persistent profile with use_profile first. Omit to leave unchanged. The choice survives MCP restarts; restart=False applies it on the next launch.",
+  "title": "Startup Mode"
+}
    • addedInput schema / properties / startup_urls
      Added value: +{
+  "anyOf": [
+    {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "One or more absolute HTTP(S) URLs, required with startup_mode='urls'. Only valid together with that mode.",
+  "title": "Startup Urls"
+}
  2. Changed1 schema field changedv2.5.0
    • 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"
+}
  3. First observedv1.7.2

TDQS

A4.3/5.0
Behavior5/5

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

Adds rich behavior beyond annotations: applying flags restarts Chrome and closes every open page, dropping cookies on ephemeral profiles; values override NODRIVER_ENABLE_* env vars; startup mode persists per profile and survives MCP server restarts; saved MCP choices take precedence over Chrome's setting. This goes well past the destructiveHint/idempotentHint annotations.

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

Conciseness4/5

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

Front-loads the core action and read form, then layers persistence and precedence details. Slightly dense across many paragraphs, but each sentence carries non-redundant information; no padding.

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

Completeness4/5

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

An output schema exists, so return values needn't be explained. For a 7-param destructive mutation tool with per-profile persistence quirks, the description covers the critical behavioral hazards (restart side effects, env var override, persistence precedence) well.

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 coverage is 100%, so each parameter is already documented in the schema. The description adds cross-parameter semantics (startup_urls only valid with startup_mode='urls', startup_mode persistence, restart interplay) but largely reinforces schema content. Baseline 3 with slight added value.

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?

States a specific verb and resource ('Change Chrome's launch flags at runtime') and immediately distinguishes the read-only invocation ('call with no arguments at all to just read the effective configuration'). An agent can tell what this does and its dual form without opening the schema.

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?

Gives clear when-to-use context: the no-argument read form, and the note that manage_extensions (a named sibling) offers the same extensions switch plus listing/loading. It explains restart=False deferral behavior. It lacks explicit 'do not use this when' exclusions for startup_mode vs use_profile ordering, but context is strong.

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

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