diff --git a/package.json b/package.json
index ee9d741..596c43d 100644
--- a/package.json
+++ b/package.json
@@ -17,8 +17,9 @@
   "license": "Apache-2.0",
   "scripts": {
     "build": "tsc",
-    "lint": "npm run update-readme && eslint . && tsc --noEmit",
+    "lint": "npm run update-readme && npm run check-deps && eslint . && tsc --noEmit",
     "lint-fix": "eslint . --fix",
+    "check-deps": "node utils/check-deps.js",
     "update-readme": "node utils/update-readme.js",
     "watch": "tsc --watch",
     "test": "playwright test",
diff --git a/src/DEPS.list b/src/DEPS.list
new file mode 100644
index 0000000..c6b6794
--- /dev/null
+++ b/src/DEPS.list
@@ -0,0 +1,6 @@
+[*]
+./tools/
+./mcp/
+
+[program.ts]
+***
diff --git a/src/extension/DEPS.list b/src/extension/DEPS.list
new file mode 100644
index 0000000..69e525a
--- /dev/null
+++ b/src/extension/DEPS.list
@@ -0,0 +1,3 @@
+[*]
+../
+../mcp/
diff --git a/src/loopTools/DEPS.list b/src/loopTools/DEPS.list
new file mode 100644
index 0000000..2da9aac
--- /dev/null
+++ b/src/loopTools/DEPS.list
@@ -0,0 +1,4 @@
+[*]
+../
+../loop/
+../mcp/
diff --git a/src/mcp/DEPS.list b/src/mcp/DEPS.list
new file mode 100644
index 0000000..0ba24e6
--- /dev/null
+++ b/src/mcp/DEPS.list
@@ -0,0 +1,4 @@
+[*]
+../log.js
+../manualPromise.js
+../httpServer.js
diff --git a/src/tools/DEPS.list b/src/tools/DEPS.list
new file mode 100644
index 0000000..2467fe7
--- /dev/null
+++ b/src/tools/DEPS.list
@@ -0,0 +1,4 @@
+[*]
+../javascript.js
+../log.js
+../manualPromise.js
diff --git a/utils/check-deps.js b/utils/check-deps.js
new file mode 100644
index 0000000..884f660
--- /dev/null
+++ b/utils/check-deps.js
@@ -0,0 +1,179 @@
+#!/usr/bin/env node
+/**
+ * Copyright 2019 Google Inc. All rights reserved.
+ * Modifications copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// @ts-check
+
+import fs from 'fs';
+import ts from 'typescript';
+import path from 'path';
+
+const __dirname = path.dirname(new URL(import.meta.url).pathname);
+
+const depsCache = {};
+const packageRoot = path.resolve(__dirname, '..');
+
+async function checkDeps() {
+  const deps = new Set();
+  const src = path.join(packageRoot, 'src');
+
+  const program = ts.createProgram({
+    options: {
+      allowJs: true,
+      target: ts.ScriptTarget.ESNext,
+      strict: true,
+    },
+    rootNames: listAllFiles(src),
+  });
+  const sourceFiles = program.getSourceFiles();
+  const errors = [];
+  sourceFiles.filter(x => !x.fileName.includes(path.sep + 'node_modules' + path.sep) && !x.fileName.includes(path.sep + 'bundles' + path.sep)).map(x => visit(x, x.fileName, x.getFullText()));
+
+  if (errors.length) {
+    for (const error of errors)
+      console.log(error);
+    console.log(`--------------------------------------------------------`);
+    console.log(`Changing the project structure or adding new components?`);
+    console.log(`Update DEPS in ${packageRoot}`);
+    console.log(`--------------------------------------------------------`);
+    process.exit(1);
+  }
+
+  function visit(node, fileName, text) {
+    if (ts.isImportDeclaration(node) && ts.isStringLiteral(node.moduleSpecifier)) {
+      if (node.importClause) {
+        if (node.importClause.isTypeOnly)
+          return;
+        if (node.importClause.namedBindings && ts.isNamedImports(node.importClause.namedBindings)) {
+          if (node.importClause.namedBindings.elements.every(e => e.isTypeOnly))
+            return;
+        }
+      }
+      const importName = node.moduleSpecifier.text;
+      let importPath;
+      if (importName.startsWith('.'))
+        importPath = path.resolve(path.dirname(fileName), importName);
+
+      const mergedDeps = calculateDeps(fileName);
+      if (mergedDeps.includes('***'))
+        return;
+      if (importPath) {
+        if (!fs.existsSync(importPath)) {
+          if (fs.existsSync(importPath + '.ts'))
+            importPath = importPath + '.ts';
+          else if (fs.existsSync(importPath + '.tsx'))
+            importPath = importPath + '.tsx';
+          else if (fs.existsSync(importPath + '.d.ts'))
+            importPath = importPath + '.d.ts';
+        }
+
+        if (!allowImport(fileName, importPath, mergedDeps))
+          errors.push(`Disallowed import ${path.relative(packageRoot, importPath)} in ${path.relative(packageRoot, fileName)}`);
+        return;
+      }
+
+      const fullStart = node.getFullStart();
+      const commentRanges = ts.getLeadingCommentRanges(text, fullStart);
+      for (const range of commentRanges || []) {
+          const comment = text.substring(range.pos, range.end);
+          if (comment.includes('@no-check-deps'))
+            return;
+      }
+
+      if (importName.startsWith('@'))
+        deps.add(importName.split('/').slice(0, 2).join('/'));
+      else
+        deps.add(importName.split('/')[0]);
+    }
+    ts.forEachChild(node, x => visit(x, fileName, text));
+  }
+
+  function calculateDeps(from) {
+    const fromDirectory = path.dirname(from);
+    let depsDirectory = fromDirectory;
+    while (depsDirectory.startsWith(packageRoot) && !depsCache[depsDirectory] && !fs.existsSync(path.join(depsDirectory, 'DEPS.list')))
+      depsDirectory = path.dirname(depsDirectory);
+    if (!depsDirectory.startsWith(packageRoot))
+      return [];
+
+    let deps = depsCache[depsDirectory];
+    if (!deps) {
+      const depsListFile = path.join(depsDirectory, 'DEPS.list');
+      deps = {};
+      let group = [];
+      for (const line of fs.readFileSync(depsListFile, 'utf-8').split('\n').filter(Boolean).filter(l => !l.startsWith('#'))) {
+        const groupMatch = line.match(/\[(.*)\]/);
+        if (groupMatch) {
+          group = [];
+          deps[groupMatch[1]] = group;
+          continue;
+        }
+        if (line === '***')
+          group.push('***');
+        else
+          group.push(path.resolve(depsDirectory, line));
+      }
+      depsCache[depsDirectory] = deps;
+    }
+
+    return [...(deps['*'] || []), ...(deps[path.relative(depsDirectory, from)] || [])]
+  }
+
+  function allowImport(from, to, mergedDeps) {
+    const fromDirectory = path.dirname(from);
+    const toDirectory = isDirectory(to) ? to : path.dirname(to);
+    if (to === toDirectory)
+      to = path.join(to, 'index.ts');
+    if (fromDirectory === toDirectory)
+      return true;
+
+    for (const dep of mergedDeps) {
+      if (dep === '***')
+        return true;
+      if (to === dep || toDirectory === dep)
+        return true;
+      if (dep.endsWith('**')) {
+        const parent = dep.substring(0, dep.length - 2);
+        if (to.startsWith(parent))
+          return true;
+      }
+    }
+    return false;
+  }
+}
+
+function listAllFiles(dir) {
+  const dirs = fs.readdirSync(dir, { withFileTypes: true });
+  const result = [];
+  dirs.forEach(d => {
+    const res = path.resolve(dir, d.name);
+    if (d.isDirectory())
+      result.push(...listAllFiles(res));
+    else
+      result.push(res);
+  });
+  return result;
+}
+
+checkDeps().catch(e => {
+  console.error(e && e.stack ? e.stack : e);
+  process.exit(1);
+});
+
+function isDirectory(dir) {
+  return fs.existsSync(dir) && fs.statSync(dir).isDirectory();
+}