fix(mcp): catch redirect-required error in execute + always test on save

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: waleedlatif1

apps/sim/app/api/mcp/tools/execute/route.ts

@@ -9,6 +9,7 @@ import type { SubscriptionPlan } from '@/lib/core/rate-limiter/types'
 import { withRouteHandler } from '@/lib/core/utils/with-route-handler'
 import { SIM_VIA_HEADER } from '@/lib/execution/call-chain'
 import { getParsedBody, withMcpAuth } from '@/lib/mcp/middleware'
+import { McpOauthRedirectRequired } from '@/lib/mcp/oauth'
 import { mcpService } from '@/lib/mcp/service'
 import {
   McpOauthAuthorizationRequiredError,
@@ -227,6 +228,7 @@ export const POST = withRouteHandler(
     } catch (error) {
       if (
         error instanceof McpOauthAuthorizationRequiredError ||
+        error instanceof McpOauthRedirectRequired ||
         error instanceof UnauthorizedError
       ) {
         const serverId =

apps/sim/app/workspace/[workspaceId]/settings/components/mcp/components/mcp-server-form-modal/mcp-server-form-modal.tsx

@@ -505,19 +505,24 @@ export function McpServerFormModal({
       const headers = headersToRecord(formData.headers)
       const oauthClientId = formData.oauthClientId?.trim()
       const oauthClientSecret = formData.oauthClientSecret?.trim()
-      const skipTest = !!oauthClientId
-
-      if (!skipTest) {
-        const connectionResult = await testConnection({
-          name: formData.name,
-          transport: formData.transport,
-          url: formData.url!,
-          headers,
-          timeout: formData.timeout,
-          workspaceId,
-        })
-
-        if (!connectionResult.success) {
+
+      const connectionResult = await testConnection({
+        name: formData.name,
+        transport: formData.transport,
+        url: formData.url!,
+        headers,
+        timeout: formData.timeout,
+        workspaceId,
+      })
+
+      if (!connectionResult.success) {
+        const errorText = (connectionResult.error || '').toLowerCase()
+        const looksLikeAuthRequired =
+          errorText.includes('401') ||
+          errorText.includes('unauthorized') ||
+          errorText.includes('oauth') ||
+          errorText.includes('authentication')
+        if (!(oauthClientId && looksLikeAuthRequired)) {
           setSubmitError(
             connectionResult.error || 'Connection test failed. Please check the URL and try again.'
           )