diff --git a/api/server/services/MCP.js b/api/server/services/MCP.js
index d00b4053d3..0c351996fa 100644
--- a/api/server/services/MCP.js
+++ b/api/server/services/MCP.js
@@ -35,6 +35,7 @@ const {
   hasRuntimeUrlPlaceholders,
   containsGraphTokenPlaceholder,
   isOAuthServer,
+  OpenIDReauthRequiredError,
 } = require('@librechat/api');
 const {
   Time,
@@ -1125,6 +1126,11 @@ function createToolInstance({
         error,
       );
 
+      /** Carries the actionable re-auth message; the substring heuristic below would misreport it as an OAuth configuration problem */
+      if (error instanceof OpenIDReauthRequiredError) {
+        throw error;
+      }
+
       /** OAuth error, provide a helpful message */
       const isOAuthError =
         error.message?.includes('401') ||
diff --git a/api/server/services/MCP.spec.js b/api/server/services/MCP.spec.js
index c03d0e8902..976e6f81e8 100644
--- a/api/server/services/MCP.spec.js
+++ b/api/server/services/MCP.spec.js
@@ -1642,6 +1642,54 @@ describe('User parameter passing tests', () => {
       );
     });
 
+    it('preserves OpenIDReauthRequiredError through the OAuth error classification', async () => {
+      const { OpenIDReauthRequiredError } = require('@librechat/api');
+      const mockUser = { id: 'reauth-user', role: 'USER' };
+      const mockRes = { write: jest.fn(), flush: jest.fn() };
+      const { getRoleByName } = require('~/models');
+      getRoleByName.mockResolvedValue({
+        permissions: {
+          [PermissionTypes.MCP_SERVERS]: {
+            [Permissions.USE]: true,
+          },
+        },
+      });
+      const reauthError = new OpenIDReauthRequiredError(
+        'OpenID token is expired or unavailable; re-authentication is required to resolve {{LIBRECHAT_OPENID_ACCESS_TOKEN}}.',
+      );
+      mockGetMCPManager.mockReturnValue({
+        callTool: jest.fn().mockRejectedValue(reauthError),
+      });
+
+      const mcpTool = await createMCPTool({
+        res: mockRes,
+        user: mockUser,
+        config: { requiresOAuth: false },
+        toolKey: `test-tool${D}test-server`,
+        provider: 'openai',
+        userMCPAuthMap: {},
+        availableTools: {
+          [`test-tool${D}test-server`]: {
+            function: {
+              description: 'Cached tool',
+              parameters: { type: 'object', properties: {} },
+            },
+          },
+        },
+      });
+
+      await expect(
+        mcpTool.invoke(
+          {},
+          {
+            configurable: { user: mockUser },
+            metadata: { provider: 'openai', thread_id: 'thread-1', run_id: 'run-1' },
+            toolCall: {},
+          },
+        ),
+      ).rejects.toBe(reauthError);
+    });
+
     it('does not label OBO authentication failures as unconfigured MCP OAuth', async () => {
       const mockUser = { id: 'obo-user', role: 'USER' };
       const mockRes = { write: jest.fn(), flush: jest.fn() };