diff --git a/packages/core/src/mcp/token-storage/hybrid-token-storage.test.ts b/packages/core/src/mcp/token-storage/hybrid-token-storage.test.ts
new file mode 100644
index 0000000000..5303d84770
--- /dev/null
+++ b/packages/core/src/mcp/token-storage/hybrid-token-storage.test.ts
@@ -0,0 +1,274 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import { HybridTokenStorage } from './hybrid-token-storage.js';
+import { KeychainTokenStorage } from './keychain-token-storage.js';
+import { FileTokenStorage } from './file-token-storage.js';
+import { type OAuthCredentials, TokenStorageType } from './types.js';
+
+vi.mock('./keychain-token-storage.js', () => ({
+  KeychainTokenStorage: vi.fn().mockImplementation(() => ({
+    isAvailable: vi.fn(),
+    getCredentials: vi.fn(),
+    setCredentials: vi.fn(),
+    deleteCredentials: vi.fn(),
+    listServers: vi.fn(),
+    getAllCredentials: vi.fn(),
+    clearAll: vi.fn(),
+  })),
+}));
+
+vi.mock('./file-token-storage.js', () => ({
+  FileTokenStorage: vi.fn().mockImplementation(() => ({
+    getCredentials: vi.fn(),
+    setCredentials: vi.fn(),
+    deleteCredentials: vi.fn(),
+    listServers: vi.fn(),
+    getAllCredentials: vi.fn(),
+    clearAll: vi.fn(),
+  })),
+}));
+
+interface MockStorage {
+  isAvailable?: ReturnType<typeof vi.fn>;
+  getCredentials: ReturnType<typeof vi.fn>;
+  setCredentials: ReturnType<typeof vi.fn>;
+  deleteCredentials: ReturnType<typeof vi.fn>;
+  listServers: ReturnType<typeof vi.fn>;
+  getAllCredentials: ReturnType<typeof vi.fn>;
+  clearAll: ReturnType<typeof vi.fn>;
+}
+
+describe('HybridTokenStorage', () => {
+  let storage: HybridTokenStorage;
+  let mockKeychainStorage: MockStorage;
+  let mockFileStorage: MockStorage;
+  const originalEnv = process.env;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    process.env = { ...originalEnv };
+
+    // Create mock instances before creating HybridTokenStorage
+    mockKeychainStorage = {
+      isAvailable: vi.fn(),
+      getCredentials: vi.fn(),
+      setCredentials: vi.fn(),
+      deleteCredentials: vi.fn(),
+      listServers: vi.fn(),
+      getAllCredentials: vi.fn(),
+      clearAll: vi.fn(),
+    };
+
+    mockFileStorage = {
+      getCredentials: vi.fn(),
+      setCredentials: vi.fn(),
+      deleteCredentials: vi.fn(),
+      listServers: vi.fn(),
+      getAllCredentials: vi.fn(),
+      clearAll: vi.fn(),
+    };
+
+    (
+      KeychainTokenStorage as unknown as ReturnType<typeof vi.fn>
+    ).mockImplementation(() => mockKeychainStorage);
+    (
+      FileTokenStorage as unknown as ReturnType<typeof vi.fn>
+    ).mockImplementation(() => mockFileStorage);
+
+    storage = new HybridTokenStorage('test-service');
+  });
+
+  afterEach(() => {
+    process.env = originalEnv;
+  });
+
+  describe('storage selection', () => {
+    it('should use keychain when available', async () => {
+      mockKeychainStorage.isAvailable!.mockResolvedValue(true);
+      mockKeychainStorage.getCredentials.mockResolvedValue(null);
+
+      await storage.getCredentials('test-server');
+
+      expect(mockKeychainStorage.isAvailable).toHaveBeenCalled();
+      expect(mockKeychainStorage.getCredentials).toHaveBeenCalledWith(
+        'test-server',
+      );
+      expect(await storage.getStorageType()).toBe(TokenStorageType.KEYCHAIN);
+    });
+
+    it('should use file storage when GEMINI_FORCE_FILE_STORAGE is set', async () => {
+      process.env['GEMINI_FORCE_FILE_STORAGE'] = 'true';
+      mockFileStorage.getCredentials.mockResolvedValue(null);
+
+      await storage.getCredentials('test-server');
+
+      expect(mockKeychainStorage.isAvailable).not.toHaveBeenCalled();
+      expect(mockFileStorage.getCredentials).toHaveBeenCalledWith(
+        'test-server',
+      );
+      expect(await storage.getStorageType()).toBe(
+        TokenStorageType.ENCRYPTED_FILE,
+      );
+    });
+
+    it('should fall back to file storage when keychain is unavailable', async () => {
+      mockKeychainStorage.isAvailable!.mockResolvedValue(false);
+      mockFileStorage.getCredentials.mockResolvedValue(null);
+
+      await storage.getCredentials('test-server');
+
+      expect(mockKeychainStorage.isAvailable).toHaveBeenCalled();
+      expect(mockFileStorage.getCredentials).toHaveBeenCalledWith(
+        'test-server',
+      );
+      expect(await storage.getStorageType()).toBe(
+        TokenStorageType.ENCRYPTED_FILE,
+      );
+    });
+
+    it('should fall back to file storage when keychain throws error', async () => {
+      mockKeychainStorage.isAvailable!.mockRejectedValue(
+        new Error('Keychain error'),
+      );
+      mockFileStorage.getCredentials.mockResolvedValue(null);
+
+      await storage.getCredentials('test-server');
+
+      expect(mockKeychainStorage.isAvailable).toHaveBeenCalled();
+      expect(mockFileStorage.getCredentials).toHaveBeenCalledWith(
+        'test-server',
+      );
+      expect(await storage.getStorageType()).toBe(
+        TokenStorageType.ENCRYPTED_FILE,
+      );
+    });
+
+    it('should cache storage selection', async () => {
+      mockKeychainStorage.isAvailable!.mockResolvedValue(true);
+      mockKeychainStorage.getCredentials.mockResolvedValue(null);
+
+      await storage.getCredentials('test-server');
+      await storage.getCredentials('another-server');
+
+      expect(mockKeychainStorage.isAvailable).toHaveBeenCalledTimes(1);
+    });
+  });
+
+  describe('getCredentials', () => {
+    it('should delegate to selected storage', async () => {
+      const credentials: OAuthCredentials = {
+        serverName: 'test-server',
+        token: {
+          accessToken: 'access-token',
+          tokenType: 'Bearer',
+        },
+        updatedAt: Date.now(),
+      };
+
+      mockKeychainStorage.isAvailable!.mockResolvedValue(true);
+      mockKeychainStorage.getCredentials.mockResolvedValue(credentials);
+
+      const result = await storage.getCredentials('test-server');
+
+      expect(result).toEqual(credentials);
+      expect(mockKeychainStorage.getCredentials).toHaveBeenCalledWith(
+        'test-server',
+      );
+    });
+  });
+
+  describe('setCredentials', () => {
+    it('should delegate to selected storage', async () => {
+      const credentials: OAuthCredentials = {
+        serverName: 'test-server',
+        token: {
+          accessToken: 'access-token',
+          tokenType: 'Bearer',
+        },
+        updatedAt: Date.now(),
+      };
+
+      mockKeychainStorage.isAvailable!.mockResolvedValue(true);
+      mockKeychainStorage.setCredentials.mockResolvedValue(undefined);
+
+      await storage.setCredentials(credentials);
+
+      expect(mockKeychainStorage.setCredentials).toHaveBeenCalledWith(
+        credentials,
+      );
+    });
+  });
+
+  describe('deleteCredentials', () => {
+    it('should delegate to selected storage', async () => {
+      mockKeychainStorage.isAvailable!.mockResolvedValue(true);
+      mockKeychainStorage.deleteCredentials.mockResolvedValue(undefined);
+
+      await storage.deleteCredentials('test-server');
+
+      expect(mockKeychainStorage.deleteCredentials).toHaveBeenCalledWith(
+        'test-server',
+      );
+    });
+  });
+
+  describe('listServers', () => {
+    it('should delegate to selected storage', async () => {
+      const servers = ['server1', 'server2'];
+      mockKeychainStorage.isAvailable!.mockResolvedValue(true);
+      mockKeychainStorage.listServers.mockResolvedValue(servers);
+
+      const result = await storage.listServers();
+
+      expect(result).toEqual(servers);
+      expect(mockKeychainStorage.listServers).toHaveBeenCalled();
+    });
+  });
+
+  describe('getAllCredentials', () => {
+    it('should delegate to selected storage', async () => {
+      const credentialsMap = new Map([
+        [
+          'server1',
+          {
+            serverName: 'server1',
+            token: { accessToken: 'token1', tokenType: 'Bearer' },
+            updatedAt: Date.now(),
+          },
+        ],
+        [
+          'server2',
+          {
+            serverName: 'server2',
+            token: { accessToken: 'token2', tokenType: 'Bearer' },
+            updatedAt: Date.now(),
+          },
+        ],
+      ]);
+
+      mockKeychainStorage.isAvailable!.mockResolvedValue(true);
+      mockKeychainStorage.getAllCredentials.mockResolvedValue(credentialsMap);
+
+      const result = await storage.getAllCredentials();
+
+      expect(result).toEqual(credentialsMap);
+      expect(mockKeychainStorage.getAllCredentials).toHaveBeenCalled();
+    });
+  });
+
+  describe('clearAll', () => {
+    it('should delegate to selected storage', async () => {
+      mockKeychainStorage.isAvailable!.mockResolvedValue(true);
+      mockKeychainStorage.clearAll.mockResolvedValue(undefined);
+
+      await storage.clearAll();
+
+      expect(mockKeychainStorage.clearAll).toHaveBeenCalled();
+    });
+  });
+});
diff --git a/packages/core/src/mcp/token-storage/hybrid-token-storage.ts b/packages/core/src/mcp/token-storage/hybrid-token-storage.ts
new file mode 100644
index 0000000000..70edac07cd
--- /dev/null
+++ b/packages/core/src/mcp/token-storage/hybrid-token-storage.ts
@@ -0,0 +1,97 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { BaseTokenStorage } from './base-token-storage.js';
+import { FileTokenStorage } from './file-token-storage.js';
+import type { TokenStorage, OAuthCredentials } from './types.js';
+import { TokenStorageType } from './types.js';
+
+const FORCE_FILE_STORAGE_ENV_VAR = 'GEMINI_FORCE_FILE_STORAGE';
+
+export class HybridTokenStorage extends BaseTokenStorage {
+  private storage: TokenStorage | null = null;
+  private storageType: TokenStorageType | null = null;
+  private storageInitPromise: Promise<TokenStorage> | null = null;
+
+  constructor(serviceName: string) {
+    super(serviceName);
+  }
+
+  private async initializeStorage(): Promise<TokenStorage> {
+    const forceFileStorage = process.env[FORCE_FILE_STORAGE_ENV_VAR] === 'true';
+
+    if (!forceFileStorage) {
+      try {
+        const { KeychainTokenStorage } = await import(
+          './keychain-token-storage.js'
+        );
+        const keychainStorage = new KeychainTokenStorage(this.serviceName);
+
+        const isAvailable = await keychainStorage.isAvailable();
+        if (isAvailable) {
+          this.storage = keychainStorage;
+          this.storageType = TokenStorageType.KEYCHAIN;
+          return this.storage;
+        }
+      } catch (_e) {
+        // Fallback to file storage if keychain fails to initialize
+      }
+    }
+
+    this.storage = new FileTokenStorage(this.serviceName);
+    this.storageType = TokenStorageType.ENCRYPTED_FILE;
+    return this.storage;
+  }
+
+  private async getStorage(): Promise<TokenStorage> {
+    if (this.storage !== null) {
+      return this.storage;
+    }
+
+    // Use a single initialization promise to avoid race conditions
+    if (!this.storageInitPromise) {
+      this.storageInitPromise = this.initializeStorage();
+    }
+
+    // Wait for initialization to complete
+    return await this.storageInitPromise;
+  }
+
+  async getCredentials(serverName: string): Promise<OAuthCredentials | null> {
+    const storage = await this.getStorage();
+    return storage.getCredentials(serverName);
+  }
+
+  async setCredentials(credentials: OAuthCredentials): Promise<void> {
+    const storage = await this.getStorage();
+    await storage.setCredentials(credentials);
+  }
+
+  async deleteCredentials(serverName: string): Promise<void> {
+    const storage = await this.getStorage();
+    await storage.deleteCredentials(serverName);
+  }
+
+  async listServers(): Promise<string[]> {
+    const storage = await this.getStorage();
+    return storage.listServers();
+  }
+
+  async getAllCredentials(): Promise<Map<string, OAuthCredentials>> {
+    const storage = await this.getStorage();
+    return storage.getAllCredentials();
+  }
+
+  async clearAll(): Promise<void> {
+    const storage = await this.getStorage();
+    await storage.clearAll();
+  }
+
+  async getStorageType(): Promise<TokenStorageType> {
+    await this.getStorage();
+    return this.storageType!;
+  }
+}
diff --git a/packages/core/src/mcp/token-storage/keychain-token-storage.test.ts b/packages/core/src/mcp/token-storage/keychain-token-storage.test.ts
new file mode 100644
index 0000000000..5b34ed01b5
--- /dev/null
+++ b/packages/core/src/mcp/token-storage/keychain-token-storage.test.ts
@@ -0,0 +1,352 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
+import type { KeychainTokenStorage } from './keychain-token-storage.js';
+import type { OAuthCredentials } from './types.js';
+
+// Hoist the mock to be available in the vi.mock factory
+const mockKeytar = vi.hoisted(() => ({
+  getPassword: vi.fn(),
+  setPassword: vi.fn(),
+  deletePassword: vi.fn(),
+  findCredentials: vi.fn(),
+}));
+
+const mockServiceName = 'service-name';
+const mockCryptoRandomBytesString = 'random-string';
+
+// Mock the dynamic import of 'keytar'
+vi.mock('keytar', () => ({
+  default: mockKeytar,
+}));
+
+vi.mock('node:crypto', () => ({
+  randomBytes: vi.fn(() => ({
+    toString: vi.fn(() => mockCryptoRandomBytesString),
+  })),
+}));
+
+describe('KeychainTokenStorage', () => {
+  let storage: KeychainTokenStorage;
+
+  beforeEach(async () => {
+    vi.resetAllMocks();
+    // Reset the internal state of the keychain-token-storage module
+    vi.resetModules();
+    const { KeychainTokenStorage } = await import(
+      './keychain-token-storage.js'
+    );
+    storage = new KeychainTokenStorage(mockServiceName);
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+    vi.useRealTimers();
+  });
+
+  const validCredentials = {
+    serverName: 'test-server',
+    token: {
+      accessToken: 'access-token',
+      tokenType: 'Bearer',
+      expiresAt: Date.now() + 3600000,
+    },
+    updatedAt: Date.now(),
+  } as OAuthCredentials;
+
+  describe('checkKeychainAvailability', () => {
+    it('should return true if keytar is available and functional', async () => {
+      mockKeytar.setPassword.mockResolvedValue(undefined);
+      mockKeytar.getPassword.mockResolvedValue('test');
+      mockKeytar.deletePassword.mockResolvedValue(true);
+
+      const isAvailable = await storage.checkKeychainAvailability();
+      expect(isAvailable).toBe(true);
+      expect(mockKeytar.setPassword).toHaveBeenCalledWith(
+        mockServiceName,
+        `__keychain_test__${mockCryptoRandomBytesString}`,
+        'test',
+      );
+      expect(mockKeytar.getPassword).toHaveBeenCalledWith(
+        mockServiceName,
+        `__keychain_test__${mockCryptoRandomBytesString}`,
+      );
+      expect(mockKeytar.deletePassword).toHaveBeenCalledWith(
+        mockServiceName,
+        `__keychain_test__${mockCryptoRandomBytesString}`,
+      );
+    });
+
+    it('should return false if keytar fails to set password', async () => {
+      mockKeytar.setPassword.mockRejectedValue(new Error('write error'));
+      const isAvailable = await storage.checkKeychainAvailability();
+      expect(isAvailable).toBe(false);
+    });
+
+    it('should return false if retrieved password does not match', async () => {
+      mockKeytar.setPassword.mockResolvedValue(undefined);
+      mockKeytar.getPassword.mockResolvedValue('wrong-password');
+      mockKeytar.deletePassword.mockResolvedValue(true);
+      const isAvailable = await storage.checkKeychainAvailability();
+      expect(isAvailable).toBe(false);
+    });
+
+    it('should cache the availability result', async () => {
+      mockKeytar.setPassword.mockResolvedValue(undefined);
+      mockKeytar.getPassword.mockResolvedValue('test');
+      mockKeytar.deletePassword.mockResolvedValue(true);
+
+      await storage.checkKeychainAvailability();
+      await storage.checkKeychainAvailability();
+
+      expect(mockKeytar.setPassword).toHaveBeenCalledTimes(1);
+    });
+  });
+
+  describe('with keychain unavailable', () => {
+    beforeEach(async () => {
+      // Force keychain to be unavailable
+      mockKeytar.setPassword.mockRejectedValue(new Error('keychain error'));
+      await storage.checkKeychainAvailability();
+    });
+
+    it('getCredentials should throw', async () => {
+      await expect(storage.getCredentials('server')).rejects.toThrow(
+        'Keychain is not available',
+      );
+    });
+
+    it('setCredentials should throw', async () => {
+      await expect(storage.setCredentials(validCredentials)).rejects.toThrow(
+        'Keychain is not available',
+      );
+    });
+
+    it('deleteCredentials should throw', async () => {
+      await expect(storage.deleteCredentials('server')).rejects.toThrow(
+        'Keychain is not available',
+      );
+    });
+
+    it('listServers should throw', async () => {
+      await expect(storage.listServers()).rejects.toThrow(
+        'Keychain is not available',
+      );
+    });
+
+    it('getAllCredentials should throw', async () => {
+      await expect(storage.getAllCredentials()).rejects.toThrow(
+        'Keychain is not available',
+      );
+    });
+  });
+
+  describe('with keychain available', () => {
+    beforeEach(async () => {
+      mockKeytar.setPassword.mockResolvedValue(undefined);
+      mockKeytar.getPassword.mockResolvedValue('test');
+      mockKeytar.deletePassword.mockResolvedValue(true);
+      await storage.checkKeychainAvailability();
+      // Reset mocks after availability check
+      vi.resetAllMocks();
+    });
+
+    describe('getCredentials', () => {
+      it('should return null if no credentials are found', async () => {
+        mockKeytar.getPassword.mockResolvedValue(null);
+        const result = await storage.getCredentials('test-server');
+        expect(result).toBeNull();
+        expect(mockKeytar.getPassword).toHaveBeenCalledWith(
+          mockServiceName,
+          'test-server',
+        );
+      });
+
+      it('should return credentials if found and not expired', async () => {
+        mockKeytar.getPassword.mockResolvedValue(
+          JSON.stringify(validCredentials),
+        );
+        const result = await storage.getCredentials('test-server');
+        expect(result).toEqual(validCredentials);
+      });
+
+      it('should return null if credentials have expired', async () => {
+        const expiredCreds = {
+          ...validCredentials,
+          token: { ...validCredentials.token, expiresAt: Date.now() - 1000 },
+        };
+        mockKeytar.getPassword.mockResolvedValue(JSON.stringify(expiredCreds));
+        const result = await storage.getCredentials('test-server');
+        expect(result).toBeNull();
+      });
+
+      it('should throw if stored data is corrupted JSON', async () => {
+        mockKeytar.getPassword.mockResolvedValue('not-json');
+        await expect(storage.getCredentials('test-server')).rejects.toThrow(
+          'Failed to parse stored credentials for test-server',
+        );
+      });
+    });
+
+    describe('setCredentials', () => {
+      it('should save credentials to keychain', async () => {
+        vi.useFakeTimers();
+        mockKeytar.setPassword.mockResolvedValue(undefined);
+        await storage.setCredentials(validCredentials);
+        expect(mockKeytar.setPassword).toHaveBeenCalledWith(
+          mockServiceName,
+          'test-server',
+          JSON.stringify({ ...validCredentials, updatedAt: Date.now() }),
+        );
+      });
+
+      it('should throw if saving to keychain fails', async () => {
+        mockKeytar.setPassword.mockRejectedValue(
+          new Error('keychain write error'),
+        );
+        await expect(storage.setCredentials(validCredentials)).rejects.toThrow(
+          'keychain write error',
+        );
+      });
+    });
+
+    describe('deleteCredentials', () => {
+      it('should delete credentials from keychain', async () => {
+        mockKeytar.deletePassword.mockResolvedValue(true);
+        await storage.deleteCredentials('test-server');
+        expect(mockKeytar.deletePassword).toHaveBeenCalledWith(
+          mockServiceName,
+          'test-server',
+        );
+      });
+
+      it('should throw if no credentials were found to delete', async () => {
+        mockKeytar.deletePassword.mockResolvedValue(false);
+        await expect(storage.deleteCredentials('test-server')).rejects.toThrow(
+          'No credentials found for test-server',
+        );
+      });
+
+      it('should throw if deleting from keychain fails', async () => {
+        mockKeytar.deletePassword.mockRejectedValue(
+          new Error('keychain delete error'),
+        );
+        await expect(storage.deleteCredentials('test-server')).rejects.toThrow(
+          'keychain delete error',
+        );
+      });
+    });
+
+    describe('listServers', () => {
+      it('should return a list of server names', async () => {
+        mockKeytar.findCredentials.mockResolvedValue([
+          { account: 'server1', password: '' },
+          { account: 'server2', password: '' },
+        ]);
+        const result = await storage.listServers();
+        expect(result).toEqual(['server1', 'server2']);
+      });
+
+      it('should not include internal test keys in the server list', async () => {
+        mockKeytar.findCredentials.mockResolvedValue([
+          { account: 'server1', password: '' },
+          {
+            account: `__keychain_test__${mockCryptoRandomBytesString}`,
+            password: '',
+          },
+          { account: 'server2', password: '' },
+        ]);
+        const result = await storage.listServers();
+        expect(result).toEqual(['server1', 'server2']);
+      });
+
+      it('should return an empty array on error', async () => {
+        mockKeytar.findCredentials.mockRejectedValue(new Error('find error'));
+        const result = await storage.listServers();
+        expect(result).toEqual([]);
+      });
+    });
+
+    describe('getAllCredentials', () => {
+      it('should return a map of all valid credentials', async () => {
+        const creds2 = {
+          ...validCredentials,
+          serverName: 'server2',
+        };
+        const expiredCreds = {
+          ...validCredentials,
+          serverName: 'expired-server',
+          token: { ...validCredentials.token, expiresAt: Date.now() - 1000 },
+        };
+        const structurallyInvalidCreds = {
+          serverName: 'invalid-server',
+        };
+
+        mockKeytar.findCredentials.mockResolvedValue([
+          {
+            account: 'test-server',
+            password: JSON.stringify(validCredentials),
+          },
+          { account: 'server2', password: JSON.stringify(creds2) },
+          {
+            account: 'expired-server',
+            password: JSON.stringify(expiredCreds),
+          },
+          { account: 'bad-server', password: 'not-json' },
+          {
+            account: 'invalid-server',
+            password: JSON.stringify(structurallyInvalidCreds),
+          },
+        ]);
+
+        const result = await storage.getAllCredentials();
+        expect(result.size).toBe(2);
+        expect(result.get('test-server')).toEqual(validCredentials);
+        expect(result.get('server2')).toEqual(creds2);
+        expect(result.has('expired-server')).toBe(false);
+        expect(result.has('bad-server')).toBe(false);
+        expect(result.has('invalid-server')).toBe(false);
+      });
+    });
+
+    describe('clearAll', () => {
+      it('should delete all credentials for the service', async () => {
+        mockKeytar.findCredentials.mockResolvedValue([
+          { account: 'server1', password: '' },
+          { account: 'server2', password: '' },
+        ]);
+        mockKeytar.deletePassword.mockResolvedValue(true);
+
+        await storage.clearAll();
+
+        expect(mockKeytar.deletePassword).toHaveBeenCalledTimes(2);
+        expect(mockKeytar.deletePassword).toHaveBeenCalledWith(
+          mockServiceName,
+          'server1',
+        );
+        expect(mockKeytar.deletePassword).toHaveBeenCalledWith(
+          mockServiceName,
+          'server2',
+        );
+      });
+
+      it('should throw an aggregated error if deletions fail', async () => {
+        mockKeytar.findCredentials.mockResolvedValue([
+          { account: 'server1', password: '' },
+          { account: 'server2', password: '' },
+        ]);
+        mockKeytar.deletePassword
+          .mockResolvedValueOnce(true)
+          .mockRejectedValueOnce(new Error('delete failed'));
+
+        await expect(storage.clearAll()).rejects.toThrow(
+          'Failed to clear some credentials: delete failed',
+        );
+      });
+    });
+  });
+});
diff --git a/packages/core/src/mcp/token-storage/keychain-token-storage.ts b/packages/core/src/mcp/token-storage/keychain-token-storage.ts
new file mode 100644
index 0000000000..70eccbadf5
--- /dev/null
+++ b/packages/core/src/mcp/token-storage/keychain-token-storage.ts
@@ -0,0 +1,251 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import * as crypto from 'node:crypto';
+import { BaseTokenStorage } from './base-token-storage.js';
+import type { OAuthCredentials } from './types.js';
+
+interface Keytar {
+  getPassword(service: string, account: string): Promise<string | null>;
+  setPassword(
+    service: string,
+    account: string,
+    password: string,
+  ): Promise<void>;
+  deletePassword(service: string, account: string): Promise<boolean>;
+  findCredentials(
+    service: string,
+  ): Promise<Array<{ account: string; password: string }>>;
+}
+
+const KEYCHAIN_TEST_PREFIX = '__keychain_test__';
+
+export class KeychainTokenStorage extends BaseTokenStorage {
+  private keychainAvailable: boolean | null = null;
+  private keytarModule: Keytar | null = null;
+  private keytarLoadAttempted = false;
+
+  async getKeytar(): Promise<Keytar | null> {
+    // If we've already tried loading (successfully or not), return the result
+    if (this.keytarLoadAttempted) {
+      return this.keytarModule;
+    }
+
+    this.keytarLoadAttempted = true;
+
+    try {
+      // Try to import keytar without any timeout - let the OS handle it
+      const moduleName = 'keytar';
+      const module = await import(moduleName);
+      this.keytarModule = module.default || module;
+    } catch (error) {
+      console.error(error);
+    }
+    return this.keytarModule;
+  }
+
+  async getCredentials(serverName: string): Promise<OAuthCredentials | null> {
+    if (!(await this.checkKeychainAvailability())) {
+      throw new Error('Keychain is not available');
+    }
+
+    const keytar = await this.getKeytar();
+    if (!keytar) {
+      throw new Error('Keytar module not available');
+    }
+
+    try {
+      const sanitizedName = this.sanitizeServerName(serverName);
+      const data = await keytar.getPassword(this.serviceName, sanitizedName);
+
+      if (!data) {
+        return null;
+      }
+
+      const credentials = JSON.parse(data) as OAuthCredentials;
+
+      if (this.isTokenExpired(credentials)) {
+        return null;
+      }
+
+      return credentials;
+    } catch (error) {
+      if (error instanceof SyntaxError) {
+        throw new Error(`Failed to parse stored credentials for ${serverName}`);
+      }
+      throw error;
+    }
+  }
+
+  async setCredentials(credentials: OAuthCredentials): Promise<void> {
+    if (!(await this.checkKeychainAvailability())) {
+      throw new Error('Keychain is not available');
+    }
+
+    const keytar = await this.getKeytar();
+    if (!keytar) {
+      throw new Error('Keytar module not available');
+    }
+
+    this.validateCredentials(credentials);
+
+    const sanitizedName = this.sanitizeServerName(credentials.serverName);
+    const updatedCredentials: OAuthCredentials = {
+      ...credentials,
+      updatedAt: Date.now(),
+    };
+
+    const data = JSON.stringify(updatedCredentials);
+    await keytar.setPassword(this.serviceName, sanitizedName, data);
+  }
+
+  async deleteCredentials(serverName: string): Promise<void> {
+    if (!(await this.checkKeychainAvailability())) {
+      throw new Error('Keychain is not available');
+    }
+
+    const keytar = await this.getKeytar();
+    if (!keytar) {
+      throw new Error('Keytar module not available');
+    }
+
+    const sanitizedName = this.sanitizeServerName(serverName);
+    const deleted = await keytar.deletePassword(
+      this.serviceName,
+      sanitizedName,
+    );
+
+    if (!deleted) {
+      throw new Error(`No credentials found for ${serverName}`);
+    }
+  }
+
+  async listServers(): Promise<string[]> {
+    if (!(await this.checkKeychainAvailability())) {
+      throw new Error('Keychain is not available');
+    }
+
+    const keytar = await this.getKeytar();
+    if (!keytar) {
+      throw new Error('Keytar module not available');
+    }
+
+    try {
+      const credentials = await keytar.findCredentials(this.serviceName);
+      return credentials
+        .filter((cred) => !cred.account.startsWith(KEYCHAIN_TEST_PREFIX))
+        .map((cred: { account: string }) => cred.account);
+    } catch (error) {
+      console.error('Failed to list servers from keychain:', error);
+      return [];
+    }
+  }
+
+  async getAllCredentials(): Promise<Map<string, OAuthCredentials>> {
+    if (!(await this.checkKeychainAvailability())) {
+      throw new Error('Keychain is not available');
+    }
+
+    const keytar = await this.getKeytar();
+    if (!keytar) {
+      throw new Error('Keytar module not available');
+    }
+
+    const result = new Map<string, OAuthCredentials>();
+    try {
+      const credentials = (
+        await keytar.findCredentials(this.serviceName)
+      ).filter((c) => !c.account.startsWith(KEYCHAIN_TEST_PREFIX));
+
+      for (const cred of credentials) {
+        try {
+          const data = JSON.parse(cred.password) as OAuthCredentials;
+          if (!this.isTokenExpired(data)) {
+            result.set(cred.account, data);
+          }
+        } catch (error) {
+          console.error(
+            `Failed to parse credentials for ${cred.account}:`,
+            error,
+          );
+        }
+      }
+    } catch (error) {
+      console.error('Failed to get all credentials from keychain:', error);
+    }
+
+    return result;
+  }
+
+  async clearAll(): Promise<void> {
+    if (!(await this.checkKeychainAvailability())) {
+      throw new Error('Keychain is not available');
+    }
+
+    const servers = this.keytarModule
+      ? await this.keytarModule
+          .findCredentials(this.serviceName)
+          .then((creds) => creds.map((c) => c.account))
+          .catch((error: Error) => {
+            throw new Error(
+              `Failed to list servers for clearing: ${error.message}`,
+            );
+          })
+      : [];
+    const errors: Error[] = [];
+
+    for (const server of servers) {
+      try {
+        await this.deleteCredentials(server);
+      } catch (error) {
+        errors.push(error as Error);
+      }
+    }
+
+    if (errors.length > 0) {
+      throw new Error(
+        `Failed to clear some credentials: ${errors.map((e) => e.message).join(', ')}`,
+      );
+    }
+  }
+
+  // Checks whether or not a set-get-delete cycle with the keychain works.
+  // Returns false if any operation fails.
+  async checkKeychainAvailability(): Promise<boolean> {
+    if (this.keychainAvailable !== null) {
+      return this.keychainAvailable;
+    }
+
+    try {
+      const keytar = await this.getKeytar();
+      if (!keytar) {
+        this.keychainAvailable = false;
+        return false;
+      }
+
+      const testAccount = `${KEYCHAIN_TEST_PREFIX}${crypto.randomBytes(8).toString('hex')}`;
+      const testPassword = 'test';
+
+      await keytar.setPassword(this.serviceName, testAccount, testPassword);
+      const retrieved = await keytar.getPassword(this.serviceName, testAccount);
+      const deleted = await keytar.deletePassword(
+        this.serviceName,
+        testAccount,
+      );
+
+      const success = deleted && retrieved === testPassword;
+      this.keychainAvailable = success;
+      return success;
+    } catch (_error) {
+      this.keychainAvailable = false;
+      return false;
+    }
+  }
+
+  async isAvailable(): Promise<boolean> {
+    return this.checkKeychainAvailability();
+  }
+}
diff --git a/packages/core/src/mcp/token-storage/types.ts b/packages/core/src/mcp/token-storage/types.ts
index 4b7bca66bf..1e95a975e0 100644
--- a/packages/core/src/mcp/token-storage/types.ts
+++ b/packages/core/src/mcp/token-storage/types.ts
@@ -35,3 +35,8 @@ export interface TokenStorage {
   getAllCredentials(): Promise<Map<string, OAuthCredentials>>;
   clearAll(): Promise<void>;
 }
+
+export enum TokenStorageType {
+  KEYCHAIN = 'keychain',
+  ENCRYPTED_FILE = 'encrypted_file',
+}