diff --git a/.gitignore b/.gitignore
index 6ce556395..c63eadaa4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,4 +14,5 @@ sdk
 client/playwright-report/
 client/results.json
 client/test-results/
+client/e2e/test-results/
 mcp.json
diff --git a/client/e2e/cli-arguments.spec.ts b/client/e2e/cli-arguments.spec.ts
index a4dcdcce2..7711ea77c 100644
--- a/client/e2e/cli-arguments.spec.ts
+++ b/client/e2e/cli-arguments.spec.ts
@@ -1,14 +1,17 @@
 import { test, expect } from "@playwright/test";
 
+// Adjust the URL if your dev server runs on a different port
+const APP_URL = "http://localhost:6274/?MCP_PROXY_AUTH_TOKEN=abc123";
+
 // These tests verify that CLI arguments correctly set URL parameters
 // The CLI should parse config files and pass transport/serverUrl as URL params
-test.describe("CLI Arguments @cli", () => {
+test.describe("CLI Arguments", () => {
   test("should pass transport parameter from command line", async ({
     page,
   }) => {
     // Simulate: npx . --transport sse --server-url http://localhost:3000/sse
     await page.goto(
-      "http://localhost:6274/?transport=sse&serverUrl=http://localhost:3000/sse",
+      `${APP_URL}&transport=sse&serverUrl=http://localhost:3000/sse`,
     );
 
     // Wait for the Transport Type dropdown to be visible
@@ -29,7 +32,7 @@ test.describe("CLI Arguments @cli", () => {
   }) => {
     // Simulate config with streamable-http transport
     await page.goto(
-      "http://localhost:6274/?transport=streamable-http&serverUrl=http://localhost:3000/mcp",
+      `${APP_URL}&transport=streamable-http&serverUrl=http://localhost:3000/mcp`,
     );
 
     // Wait for the Transport Type dropdown to be visible
@@ -49,7 +52,7 @@ test.describe("CLI Arguments @cli", () => {
     page,
   }) => {
     // Simulate stdio config (no transport param needed)
-    await page.goto("http://localhost:6274/");
+    await page.goto(APP_URL);
 
     // Wait for the Transport Type dropdown to be visible
     const selectTrigger = page.getByLabel("Transport Type");
@@ -63,3 +66,28 @@ test.describe("CLI Arguments @cli", () => {
     await expect(page.locator("#arguments-input")).toBeVisible();
   });
 });
+
+test.describe("CLI npx (npm exec) start up", { tag: "@cli" }, () => {
+  test("CLI arguments should populate form fields", async ({ page }) => {
+    const cliTestScenario = process.env.CLI_TEST_SCENARIO;
+
+    // Skip this test if not running a CLI test scenario
+    if (
+      !cliTestScenario ||
+      (cliTestScenario !== "inline" && cliTestScenario !== "file")
+    ) {
+      test.skip();
+      return;
+    }
+
+    await page.goto(APP_URL);
+
+    const commandInput = page.getByRole("textbox", { name: "Command" });
+    const argsInput = page.getByRole("textbox", { name: "Arguments" });
+
+    await expect(commandInput).toHaveValue("npm");
+    await expect(argsInput).toHaveValue(
+      "--silent --prefix /path/to/mcp/servers/src/everything run start",
+    );
+  });
+});
diff --git a/client/e2e/fixtures/everything-server.json b/client/e2e/fixtures/everything-server.json
new file mode 100644
index 000000000..41ca3c669
--- /dev/null
+++ b/client/e2e/fixtures/everything-server.json
@@ -0,0 +1,18 @@
+{
+  "mcpServers": {
+    "everything": {
+      "command": "npm",
+      "args": [
+        "--silent",
+        "--prefix",
+        "/path/to/mcp/servers/src/everything",
+        "run",
+        "start"
+      ],
+      "env": {
+        "FOO": "bar",
+        "BAZ": "bat"
+      }
+    }
+  }
+}
diff --git a/client/e2e/startup-state.spec.ts b/client/e2e/startup-state.spec.ts
index 414ebd3e6..e5e10b674 100644
--- a/client/e2e/startup-state.spec.ts
+++ b/client/e2e/startup-state.spec.ts
@@ -1,7 +1,7 @@
 import { test, expect } from "@playwright/test";
 
 // Adjust the URL if your dev server runs on a different port
-const APP_URL = "http://localhost:6274/";
+const APP_URL = "http://localhost:6274/?MCP_PROXY_AUTH_TOKEN=abc123";
 
 test.describe("Startup State", () => {
   test("should not navigate to a tab when Inspector first opens", async ({
diff --git a/client/e2e/transport-type-dropdown.spec.ts b/client/e2e/transport-type-dropdown.spec.ts
index e4ac8fbb4..f4e242c51 100644
--- a/client/e2e/transport-type-dropdown.spec.ts
+++ b/client/e2e/transport-type-dropdown.spec.ts
@@ -1,7 +1,7 @@
 import { test, expect } from "@playwright/test";
 
 // Adjust the URL if your dev server runs on a different port
-const APP_URL = "http://localhost:6274/";
+const APP_URL = "http://localhost:6274/?MCP_PROXY_AUTH_TOKEN=abc123";
 
 test.describe("Transport Type Dropdown", () => {
   test("should have options for STDIO, SSE, and Streamable HTTP", async ({
diff --git a/client/package.json b/client/package.json
index d1c6d7751..d6fe85d2e 100644
--- a/client/package.json
+++ b/client/package.json
@@ -21,7 +21,9 @@
     "preview": "vite preview --port 6274",
     "test": "jest --config jest.config.cjs",
     "test:watch": "jest --config jest.config.cjs --watch",
-    "test:e2e": "playwright test e2e && npm run cleanup:e2e",
+    "test:e2e": "playwright test --grep-invert @cli e2e && npm run test:e2e:cli-file && npm run test:e2e:cli-inline && npm run cleanup:e2e",
+    "test:e2e:cli-file": "CLI_TEST_SCENARIO=file playwright test --grep @cli e2e",
+    "test:e2e:cli-inline": "CLI_TEST_SCENARIO=inline playwright test --grep @cli e2e",
     "cleanup:e2e": "node e2e/global-teardown.js"
   },
   "dependencies": {
diff --git a/client/playwright.config.ts b/client/playwright.config.ts
index 570dd054e..e4b50d120 100644
--- a/client/playwright.config.ts
+++ b/client/playwright.config.ts
@@ -1,5 +1,20 @@
 import { defineConfig, devices } from "@playwright/test";
 
+const getWebServerCommand = () => {
+  /**
+   * The content of the fixture configuration file matches the inline arguments such
+   * that the same set of tests (tagged `@cli`) can run in both scenarios.
+   */
+  switch (process.env.CLI_TEST_SCENARIO) {
+    case "file":
+      return "npx . --config client/e2e/fixtures/everything-server.json --server everything";
+    case "inline":
+      return "npx . -e FOO=bar -e BAZ=bat npm --silent --prefix /path/to/mcp/servers/src/everything run start";
+    default:
+      return "npm run dev";
+  }
+};
+
 /**
  * @see https://playwright.dev/docs/test-configuration
  */
@@ -7,9 +22,13 @@ export default defineConfig({
   /* Run your local dev server before starting the tests */
   webServer: {
     cwd: "..",
-    command: "npm run dev",
-    url: "http://localhost:6274",
+    command: getWebServerCommand(),
+    url: "http://localhost:6274/?MCP_PROXY_AUTH_TOKEN=abc123",
     reuseExistingServer: !process.env.CI,
+    env: {
+      MCP_AUTO_OPEN_ENABLED: "false",
+      MCP_PROXY_AUTH_TOKEN: "abc123",
+    },
   },
 
   testDir: "./e2e",
@@ -22,7 +41,11 @@ export default defineConfig({
   retries: process.env.CI ? 2 : 0,
   /* Opt out of parallel tests on CI. */
   workers: process.env.CI ? 1 : undefined,
-  /* Reporter to use. See https://playwright.dev/docs/test-reporters */
+
+  /* Reporter to use. See https://playwright.dev/docs/test-reporters
+   *   Use `--reporter [type]` to override for more information while debugging tests.
+   *   e.g., `npx playwright test --reporter list [args]`
+   */
   reporter: process.env.CI
     ? [
         ["html", { outputFolder: "playwright-report" }],
@@ -30,10 +53,11 @@ export default defineConfig({
         ["line"],
       ]
     : [["line"]],
+
   /* Shared settings for all the projects below. See https://playwright.dev/docs/api/class-testoptions. */
   use: {
     /* Base URL to use in actions like `await page.goto('/')`. */
-    baseURL: "http://localhost:6274",
+    baseURL: "http://localhost:6274/?MCP_PROXY_AUTH_TOKEN=abc123",
 
     /* Collect trace when retrying the failed test. See https://playwright.dev/docs/trace-viewer */
     trace: "on-first-retry",
@@ -43,6 +67,9 @@ export default defineConfig({
 
     /* Record video on failure */
     video: "retain-on-failure",
+
+    /* Useful for local debugging */
+    // headless: false,
   },
 
   /* Configure projects for major browsers */
diff --git a/package.json b/package.json
index bd494090a..41d1b89e5 100644
--- a/package.json
+++ b/package.json
@@ -37,7 +37,7 @@
     "start-client": "cd client && npm run preview",
     "test": "npm run prettier-check && cd client && npm test",
     "test-cli": "cd cli && npm run test",
-    "test:e2e": "MCP_AUTO_OPEN_ENABLED=false npm run test:e2e --workspace=client",
+    "test:e2e": "npm run test:e2e --workspace=client",
     "prettier-fix": "prettier --write .",
     "prettier-check": "prettier --check .",
     "lint": "prettier --check . && cd client && npm run lint",