diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
index de73ee8ad..bc99aa5c6 100644
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -57,14 +57,8 @@ jobs:
         shell: bash
         run: echo 0 | sudo tee /proc/sys/kernel/apparmor_restrict_unprivileged_userns
 
-      - name: Run tests (node20)
-        if: ${{ matrix.node == '20' }}
-        shell: bash
-        run: npm run test:node20
-
       - name: Run tests
         shell: bash
-        if: ${{ matrix.node != '20' }}
         run: npm run test:no-build
 
   # Gating job for branch protection.
diff --git a/GEMINI.md b/GEMINI.md
index d0eac03eb..fad71d480 100644
--- a/GEMINI.md
+++ b/GEMINI.md
@@ -1,5 +1,6 @@
 # Instructions
 
-- use `npm run build` to run tsc and test build.
-- use `npm run test` to run tests, run all tests to verify correctness.
-- use only scripts from `package.json` to run commands.
+- Use only scripts from `package.json` to run commands.
+- Use `npm run build` to run tsc and test build.
+- Use `npm run test` to build and run tests, run all tests to verify correctness.
+- use `npm run test path-to-test.ts` to build and run a single test file, for example, `npm run test tests/McpContext.test.ts`.
diff --git a/package.json b/package.json
index 562c5961e..630fb103c 100644
--- a/package.json
+++ b/package.json
@@ -16,12 +16,10 @@
     "docs:generate": "node --experimental-strip-types scripts/generate-docs.ts",
     "start": "npm run build && node build/src/index.js",
     "start-debug": "DEBUG=mcp:* DEBUG_COLORS=false npm run build && node build/src/index.js",
-    "test:node20": "node --import ./build/tests/setup.js --test-reporter spec --test-force-exit --test build/tests",
-    "test:no-build": "node --import ./build/tests/setup.js --no-warnings=ExperimentalWarning --experimental-print-required-tla --test-reporter spec --test-force-exit --test \"build/tests/**/*.test.js\"",
     "test": "npm run build && npm run test:no-build",
-    "test:only": "npm run build && npm run test:only:no-build",
-    "test:only:no-build": "node --import ./build/tests/setup.js --no-warnings=ExperimentalWarning --test-reporter spec --test-force-exit --test --test-only \"build/tests/**/*.test.js\"",
-    "test:update-snapshots": "npm run build && node --import ./build/tests/setup.js --no-warnings=ExperimentalWarning --test-force-exit --test --test-update-snapshots \"build/tests/**/*.test.js\"",
+    "test:no-build": "node scripts/test.mjs",
+    "test:only": "npm run build && node scripts/test.mjs --test-only",
+    "test:update-snapshots": "npm run build && node scripts/test.mjs --test-update-snapshots",
     "prepare": "node --experimental-strip-types scripts/prepare.ts",
     "verify-server-json-version": "node --experimental-strip-types scripts/verify-server-json-version.ts"
   },
diff --git a/scripts/test.mjs b/scripts/test.mjs
new file mode 100644
index 000000000..5e061537b
--- /dev/null
+++ b/scripts/test.mjs
@@ -0,0 +1,59 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+// Note: can be converted to ts file once node 20 support is dropped.
+// Node 20 does not support --experimental-strip-types flag.
+
+import {spawn} from 'node:child_process';
+import path from 'node:path';
+import process from 'node:process';
+
+const args = process.argv.slice(2);
+const userArgs = args.filter(arg => !arg.startsWith('-'));
+const flags = args.filter(arg => arg.startsWith('-'));
+
+const files = [];
+
+if (userArgs.length > 0) {
+  for (const arg of userArgs) {
+    // Map .ts files to build/ .js files
+    let testPath = arg;
+    if (testPath.endsWith('.ts')) {
+      testPath = testPath.replace(/\.ts$/, '.js');
+      if (!testPath.startsWith('build/')) {
+        testPath = path.join('build', testPath);
+      }
+    }
+    files.push(testPath);
+  }
+} else {
+  const isNode20 = process.version.startsWith('v20.');
+  if (isNode20) {
+    files.push('build/tests');
+  } else {
+    files.push('build/tests/**/*.test.js');
+  }
+}
+
+const nodeArgs = [
+  '--import',
+  './build/tests/setup.js',
+  '--no-warnings=ExperimentalWarning',
+  '--test-reporter',
+  'spec',
+  '--test-force-exit',
+  '--test',
+  ...flags,
+  ...files,
+];
+
+const child = spawn('node', nodeArgs, {
+  stdio: 'inherit',
+});
+
+child.on('close', code => {
+  process.exit(code ?? 1);
+});
diff --git a/scripts/tsconfig.json b/scripts/tsconfig.json
index c6c5981bf..1a65b2e08 100644
--- a/scripts/tsconfig.json
+++ b/scripts/tsconfig.json
@@ -19,5 +19,5 @@
     "noEmit": true,
     "useUnknownInCatchVariables": false
   },
-  "include": ["./**/*.ts", "./**/*.js"]
+  "include": ["./**/*.ts", "./**/*.js", "./**/*.mjs"]
 }