diff --git a/apps/sim/blocks/types.ts b/apps/sim/blocks/types.ts
index 9523b543e..def037eee 100644
--- a/apps/sim/blocks/types.ts
+++ b/apps/sim/blocks/types.ts
@@ -243,11 +243,7 @@ export interface SubBlockConfig {
   hidden?: boolean
   hideFromPreview?: boolean // Hide this subblock from the workflow block preview
   requiresFeature?: string // Environment variable name that must be truthy for this subblock to be visible
-  /**
-   * Hide this subblock when running on hosted Sim (isHosted is true).
-   * Used for tool API key fields that should be hidden when Sim provides hosted keys.
-   */
-  hideWhenHosted?: boolean
+  hideWhenHosted?: boolean // Hide this subblock when running on hosted sim
   description?: string
   tooltip?: string // Tooltip text displayed via info icon next to the title
   value?: (params: Record<string, any>) => string
diff --git a/apps/sim/serializer/index.ts b/apps/sim/serializer/index.ts
index 622667d9f..53b72e17c 100644
--- a/apps/sim/serializer/index.ts
+++ b/apps/sim/serializer/index.ts
@@ -10,6 +10,7 @@ import {
   isCanonicalPair,
   isNonEmptyValue,
   isSubBlockFeatureEnabled,
+  isSubBlockHiddenByHostedKey,
   resolveCanonicalMode,
 } from '@/lib/workflows/subblocks/visibility'
 import { getBlock } from '@/blocks'
@@ -49,6 +50,7 @@ function shouldSerializeSubBlock(
   canonicalModeOverrides?: CanonicalModeOverrides
 ): boolean {
   if (!isSubBlockFeatureEnabled(subBlockConfig)) return false
+  if (isSubBlockHiddenByHostedKey(subBlockConfig)) return false
 
   if (subBlockConfig.mode === 'trigger') {
     if (!isTriggerContext && !isTriggerCategory) return false
diff --git a/apps/sim/tools/index.ts b/apps/sim/tools/index.ts
index b94d796d5..44247e2c3 100644
--- a/apps/sim/tools/index.ts
+++ b/apps/sim/tools/index.ts
@@ -3,6 +3,7 @@ import { generateInternalToken } from '@/lib/auth/internal'
 import { getBYOKKey } from '@/lib/api-key/byok'
 import { logFixedUsage } from '@/lib/billing/core/usage-log'
 import { env } from '@/lib/core/config/env'
+import { isHosted } from '@/lib/core/config/feature-flags'
 import { DEFAULT_EXECUTION_TIMEOUT_MS } from '@/lib/core/execution-limits'
 import {
   secureFetchWithPinnedIP,
@@ -61,6 +62,7 @@ async function injectHostedKeyIfNeeded(
   requestId: string
 ): Promise<boolean> {
   if (!tool.hosting) return false
+  if (!isHosted) return false
 
   const { envKeys, apiKeyParam, byokProviderId } = tool.hosting
   const userProvidedKey = params[apiKeyParam]
diff --git a/apps/sim/tools/serper/search.ts b/apps/sim/tools/serper/search.ts
index 81861c495..4e4b22919 100644
--- a/apps/sim/tools/serper/search.ts
+++ b/apps/sim/tools/serper/search.ts
@@ -43,7 +43,7 @@ export const searchTool: ToolConfig<SearchParams, SearchResponse> = {
     },
     apiKey: {
       type: 'string',
-      required: false,
+      required: true,
       visibility: 'user-only',
       description: 'Serper API Key',
     },