feat: Allow opting out of default Chrome launch arguments (#729)

Related Issue -
#430

### Description

When Chrome is launched via Puppeteer, it automatically adds a set of
default flags like `--enable-automation --disable-extensions
--disable-component-extensions-with-background-pages.`

Currently, there is no way to opt out of these defaults, which makes
certain use cases difficult or impossible to support. this PR adds a way
to selectively ignore specific default Chrome launch flags applied by
Puppeteer using its
[ignoreDefaultArgs](https://pptr.dev/api/puppeteer.launchoptions#ignoredefaultargs)
property.

```json
{
  "name": "chrome-devtools-mcp",
  "version": "latest",
  "mcpServers": {
    "chrome-devtools": {
      "command": "npx",
      "args": [
        "chrome-devtools-mcp@latest",
        "--ignore-default-chrome-arg='--enable-automation'",
        "--ignore-default-chrome-arg='--disable-extensions'"
      ]
    }
  }
}
```

**Feedback appreciated** @OrKoN

Author: 0xlakshan

README.md

@@ -428,6 +428,10 @@ The Chrome DevTools MCP server supports the following configuration option:
   Additional arguments for Chrome. Only applies when Chrome is launched by chrome-devtools-mcp.
   - **Type:** array
 
+- **`--ignoreDefaultChromeArg`/ `--ignore-default-chrome-arg`**
+  Explicitly disable default arguments for Chrome. Only applies when Chrome is launched by chrome-devtools-mcp.
+  - **Type:** array
+
 - **`--categoryEmulation`/ `--category-emulation`**
   Set to false to exclude tools related to emulation.
   - **Type:** boolean

src/browser.ts

@@ -142,7 +142,8 @@ interface McpLaunchOptions {
     width: number;
     height: number;
   };
-  args?: string[];
+  chromeArgs?: string[];
+  ignoreDefaultChromeArgs?: string[];
   devtools: boolean;
 }
 
@@ -167,9 +168,12 @@ export async function launch(options: McpLaunchOptions): Promise<Browser> {
   }
 
   const args: LaunchOptions['args'] = [
-    ...(options.args ?? []),
+    ...(options.chromeArgs ?? []),
     '--hide-crash-restore-bubble',
   ];
+  const ignoreDefaultArgs: LaunchOptions['ignoreDefaultArgs'] =
+    options.ignoreDefaultChromeArgs ?? false;
+
   if (headless) {
     args.push('--screen-info={3840x2160}');
   }
@@ -194,6 +198,7 @@ export async function launch(options: McpLaunchOptions): Promise<Browser> {
       pipe: true,
       headless,
       args,
+      ignoreDefaultArgs: ignoreDefaultArgs,
       acceptInsecureCerts: options.acceptInsecureCerts,
       handleDevToolsAsPage: true,
     });

src/cli.ts

@@ -168,6 +168,11 @@ export const cliOptions = {
     describe:
       'Additional arguments for Chrome. Only applies when Chrome is launched by chrome-devtools-mcp.',
   },
+  ignoreDefaultChromeArg: {
+    type: 'array',
+    describe:
+      'Explicitly disable default arguments for Chrome. Only applies when Chrome is launched by chrome-devtools-mcp.',
+  },
   categoryEmulation: {
     type: 'boolean',
     default: true,
@@ -229,6 +234,10 @@ export function parseArguments(version: string, argv = process.argv) {
         `$0 --chrome-arg='--no-sandbox' --chrome-arg='--disable-setuid-sandbox'`,
         'Launch Chrome without sandboxes. Use with caution.',
       ],
+      [
+        `$0 --ignore-default-chrome-arg='--disable-extensions'`,
+        'Disable the default arguments provided by Puppeteer. Use with caution.',
+      ],
       ['$0 --no-category-emulation', 'Disable tools in the emulation category'],
       [
         '$0 --no-category-performance',

src/main.ts

@@ -54,9 +54,12 @@ server.server.setRequestHandler(SetLevelRequestSchema, () => {
 
 let context: McpContext;
 async function getContext(): Promise<McpContext> {
-  const extraArgs: string[] = (args.chromeArg ?? []).map(String);
+  const chromeArgs: string[] = (args.chromeArg ?? []).map(String);
+  const ignoreDefaultChromeArgs: string[] = (
+    args.ignoreDefaultChromeArg ?? []
+  ).map(String);
   if (args.proxyServer) {
-    extraArgs.push(`--proxy-server=${args.proxyServer}`);
+    chromeArgs.push(`--proxy-server=${args.proxyServer}`);
   }
   const devtools = args.experimentalDevtools ?? false;
   const browser =
@@ -78,7 +81,8 @@ async function getContext(): Promise<McpContext> {
           userDataDir: args.userDataDir,
           logFile,
           viewport: args.viewport,
-          args: extraArgs,
+          chromeArgs,
+          ignoreDefaultChromeArgs,
           acceptInsecureCerts: args.acceptInsecureCerts,
           devtools,
         });

tests/browser.test.ts

@@ -82,7 +82,7 @@ describe('browser', () => {
       userDataDir: folderPath,
       executablePath: executablePath(),
       devtools: false,
-      args: ['--remote-debugging-port=0'],
+      chromeArgs: ['--remote-debugging-port=0'],
     });
     try {
       const connectedBrowser = await ensureBrowserConnected({

tests/cli.test.ts

@@ -143,6 +143,30 @@ describe('cli args parsing', () => {
     });
   });
 
+  it('parses ignore chrome args', async () => {
+    const args = parseArguments('1.0.0', [
+      'node',
+      'main.js',
+      `--ignore-default-chrome-arg='--disable-extensions'`,
+      `--ignore-default-chrome-arg='--disable-cancel-all-touches'`,
+    ]);
+    assert.deepStrictEqual(args, {
+      ...defaultArgs,
+      _: [],
+      headless: false,
+      $0: 'npx chrome-devtools-mcp@latest',
+      channel: 'stable',
+      'ignore-default-chrome-arg': [
+        '--disable-extensions',
+        '--disable-cancel-all-touches',
+      ],
+      ignoreDefaultChromeArg: [
+        '--disable-extensions',
+        '--disable-cancel-all-touches',
+      ],
+    });
+  });
+
   it('parses wsEndpoint with ws:// protocol', async () => {
     const args = parseArguments('1.0.0', [
       'node',