fix: warn on unknown CLI args (#2577)

src/ToolHandler.ts

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import type {parseArguments} from './bin/chrome-devtools-mcp-cli-options.js';
+import type {ParsedArguments} from './bin/chrome-devtools-mcp-cli-options.js';
 import type {McpContext} from './McpContext.js';
 import type {McpPage} from './McpPage.js';
 import type {DataFormat} from './McpResponse.js';
@@ -46,7 +46,7 @@ function buildDisabledMessage(
 
 function getCategoryStatus(
   category: ToolCategory,
-  serverArgs: ReturnType<typeof parseArguments>,
+  serverArgs: ParsedArguments,
 ): {categoryFlag?: string; disabled: boolean} {
   const categoryFlag = buildFlag(category);
 
@@ -70,7 +70,7 @@ function getCategoryStatus(
 
 function getConditionStatus(
   condition: string,
-  serverArgs: ReturnType<typeof parseArguments>,
+  serverArgs: ParsedArguments,
 ): {conditionFlag?: string; disabled: boolean} {
   if (condition && !serverArgs[condition]) {
     return {conditionFlag: condition, disabled: true};
@@ -81,7 +81,7 @@ function getConditionStatus(
 
 function getToolStatusInfo(
   tool: ToolDefinition | DefinedPageTool,
-  serverArgs: ReturnType<typeof parseArguments>,
+  serverArgs: ParsedArguments,
 ): {disabled: boolean; reason?: string} {
   const category = tool.annotations.category;
   const categoryCheck = getCategoryStatus(category, serverArgs);
@@ -224,7 +224,7 @@ export class ToolHandler {
 
   constructor(
     private readonly tool: ToolDefinition | DefinedPageTool,
-    private readonly serverArgs: ReturnType<typeof parseArguments>,
+    private readonly serverArgs: ParsedArguments,
     private readonly getContext: () => Promise<McpContext>,
     private readonly toolMutex: Mutex,
   ) {

src/bin/chrome-devtools-mcp-cli-options.ts

@@ -384,23 +384,14 @@ export function parser(
   argv = process.argv,
   env = process.env,
 ) {
-  // Preserve yargs' mixed camel/kebab-case expansion under strict validation.
-  const kebabCaseAliases: Record<string, string> = {};
-  for (const option of Object.keys(cliOptions)) {
-    const alias = option.replace(
-      /[A-Z]/g,
-      letter => `-${letter.toLowerCase()}`,
-    );
-    if (alias !== option) {
-      kebabCaseAliases[option] = alias;
-    }
-  }
-
   const yargsInstance = yargs(hideBin(argv))
     .scriptName('npx chrome-devtools-mcp@latest')
+    .parserConfiguration({
+      'strip-aliased': true,
+      'strip-dashed': true,
+    })
     .options(cliOptions)
-    .alias(kebabCaseAliases)
-    .strictOptions()
+    .showHelpOnFail(false, 'Specify --help for available options')
     .middleware(args => {
       // We can't set default in the options else
       // Yargs will complain
@@ -418,6 +409,23 @@ export function parser(
         );
         args.usageStatistics = false;
       }
+
+      const cliOptionsAllowedArgs = [
+        ...Object.keys(cliOptions),
+        // Yargs populated with positional args
+        '_',
+        '$0',
+      ];
+
+      const unknownArgs = Object.keys(args).filter(
+        arg => !cliOptionsAllowedArgs.includes(arg),
+      );
+
+      if (unknownArgs.length > 0) {
+        console.error(
+          `Unknown arguments: ${unknownArgs.map(arg => `--${arg}`)}`,
+        );
+      }
     })
     .example([
       [

src/index.ts

@@ -6,7 +6,7 @@
 
 import type fs from 'node:fs';
 
-import type {parseArguments} from './bin/chrome-devtools-mcp-cli-options.js';
+import {type ParsedArguments} from './bin/chrome-devtools-mcp-cli-options.js';
 import type {Channel} from './browser.js';
 import {ensureBrowserConnected, ensureBrowserLaunched} from './browser.js';
 import {loadIssueDescriptions} from './devtools/issueDescriptions.js';
@@ -41,7 +41,7 @@ export {buildFlag} from './ToolHandler.js';
 const ROOTS_REQUEST_TIMEOUT = 5_000;
 
 export async function createMcpServer(
-  serverArgs: ReturnType<typeof parseArguments>,
+  serverArgs: ParsedArguments,
   options: {
     logFile?: fs.WriteStream;
   },
@@ -230,7 +230,7 @@ export async function createMcpServer(
   return {server};
 }
 
-export const logDisclaimers = (args: ReturnType<typeof parseArguments>) => {
+export const logDisclaimers = (args: ParsedArguments) => {
   console.error(
     `chrome-devtools-mcp exposes content of the browser instance to the MCP clients allowing them to inspect,
 debug, and modify any data in the browser or DevTools.

tests/cli.test.ts

@@ -17,25 +17,15 @@ function parseArguments(argv: string[], env: NodeJS.ProcessEnv = {}) {
 
 describe('cli args parsing', () => {
   const defaultArgs = {
-    'category-emulation': true,
     categoryEmulation: true,
-    'category-performance': true,
     categoryPerformance: true,
-    'category-network': true,
     categoryNetwork: true,
-    'category-extensions': false,
     categoryExtensions: false,
-    'category-experimental-third-party': false,
     categoryExperimentalThirdParty: false,
-    'auto-connect': undefined,
     autoConnect: undefined,
-    'performance-crux': true,
     performanceCrux: true,
-    'usage-statistics': true,
     usageStatistics: true,
-    'redact-network-headers': false,
     redactNetworkHeaders: false,
-    'allow-unrestricted-paths': false,
     allowUnrestrictedPaths: false,
   };
 
@@ -57,17 +47,22 @@ describe('cli args parsing', () => {
       _: [],
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
-      'browser-url': 'http://localhost:3000',
       browserUrl: 'http://localhost:3000',
-      u: 'http://localhost:3000',
     });
   });
 
   it('rejects unknown options', async () => {
-    assert.throws(
-      () => parseArguments(['--browserURL', 'http://localhost:3000']),
-      /Unknown argument: browserURL/,
-    );
+    let output = '';
+    const originalError = console.error;
+    console.error = (msg: string) => {
+      output += msg;
+    };
+    try {
+      parseArguments(['--browserURL', 'http://localhost:3000']);
+      assert.match(output, /Unknown arguments: --browserURL/);
+    } finally {
+      console.error = originalError;
+    }
   });
 
   it('parses mixed-form option names', async () => {
@@ -84,7 +79,6 @@ describe('cli args parsing', () => {
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
       channel: 'stable',
-      'user-data-dir': '/tmp/chrome-profile',
       userDataDir: '/tmp/chrome-profile',
     });
   });
@@ -96,9 +90,7 @@ describe('cli args parsing', () => {
       _: [],
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
-      'browser-url': undefined,
       browserUrl: undefined,
-      u: undefined,
       channel: 'stable',
     });
   });
@@ -110,8 +102,6 @@ describe('cli args parsing', () => {
       _: [],
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
-      'executable-path': '/tmp/test 123/chrome',
-      e: '/tmp/test 123/chrome',
       executablePath: '/tmp/test 123/chrome',
     });
   });
@@ -142,7 +132,6 @@ describe('cli args parsing', () => {
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
       channel: 'stable',
-      'chrome-arg': ['--no-sandbox', '--disable-setuid-sandbox'],
       chromeArg: ['--no-sandbox', '--disable-setuid-sandbox'],
     });
   });
@@ -158,10 +147,6 @@ describe('cli args parsing', () => {
       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',
@@ -179,9 +164,7 @@ describe('cli args parsing', () => {
       _: [],
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
-      'ws-endpoint': 'ws://127.0.0.1:9222/devtools/browser/abc123',
       wsEndpoint: 'ws://127.0.0.1:9222/devtools/browser/abc123',
-      w: 'ws://127.0.0.1:9222/devtools/browser/abc123',
     });
   });
 
@@ -195,9 +178,7 @@ describe('cli args parsing', () => {
       _: [],
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
-      'ws-endpoint': 'wss://example.com:9222/devtools/browser/abc123',
       wsEndpoint: 'wss://example.com:9222/devtools/browser/abc123',
-      w: 'wss://example.com:9222/devtools/browser/abc123',
     });
   });
 
@@ -222,7 +203,6 @@ describe('cli args parsing', () => {
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
       channel: 'stable',
-      'category-emulation': false,
       categoryEmulation: false,
     });
   });
@@ -234,7 +214,6 @@ describe('cli args parsing', () => {
       headless: false,
       $0: 'npx chrome-devtools-mcp@latest',
       channel: 'stable',
-      'auto-connect': true,
       autoConnect: true,
     });
   });