diff --git a/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/panel/components/editor/components/sub-block/components/combobox/combobox.tsx b/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/panel/components/editor/components/sub-block/components/combobox/combobox.tsx
index a8e68f47d4..df1ea3712d 100644
--- a/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/panel/components/editor/components/sub-block/components/combobox/combobox.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/panel/components/editor/components/sub-block/components/combobox/combobox.tsx
@@ -11,7 +11,7 @@ import type { SubBlockConfig } from '@/blocks/types'
 /**
  * Constants for ComboBox component behavior
  */
-const DEFAULT_MODEL = 'gpt-4o'
+const DEFAULT_MODEL = 'claude-sonnet-4-5'
 const ZOOM_FACTOR_BASE = 0.96
 const MIN_ZOOM = 0.1
 const MAX_ZOOM = 1
@@ -99,18 +99,18 @@ export function ComboBox({
 
   /**
    * Determines the default option value to use.
-   * Priority: explicit defaultValue > gpt-4o for model field > first option
+   * Priority: explicit defaultValue > claude-sonnet-4-5 for model field > first option
    */
   const defaultOptionValue = useMemo(() => {
     if (defaultValue !== undefined) {
       return defaultValue
     }
 
-    // For model field, default to gpt-4o if available
+    // For model field, default to claude-sonnet-4-5 if available
     if (subBlockId === 'model') {
-      const gpt4o = evaluatedOptions.find((opt) => getOptionValue(opt) === DEFAULT_MODEL)
-      if (gpt4o) {
-        return getOptionValue(gpt4o)
+      const claudeSonnet45 = evaluatedOptions.find((opt) => getOptionValue(opt) === DEFAULT_MODEL)
+      if (claudeSonnet45) {
+        return getOptionValue(claudeSonnet45)
       }
     }
 
diff --git a/apps/sim/blocks/blocks/agent.ts b/apps/sim/blocks/blocks/agent.ts
index 7ade8d876a..3e2c3e0829 100644
--- a/apps/sim/blocks/blocks/agent.ts
+++ b/apps/sim/blocks/blocks/agent.ts
@@ -90,6 +90,7 @@ export const AgentBlock: BlockConfig<AgentResponse> = {
       type: 'combobox',
       placeholder: 'Type or select a model...',
       required: true,
+      defaultValue: 'claude-sonnet-4-5',
       options: () => {
         const providersState = useProvidersStore.getState()
         const baseModels = providersState.providers.base.models
@@ -245,7 +246,7 @@ export const AgentBlock: BlockConfig<AgentResponse> = {
       type: 'slider',
       min: 0,
       max: 1,
-      defaultValue: 0.5,
+      defaultValue: 0.3,
       condition: () => ({
         field: 'model',
         value: (() => {
@@ -262,7 +263,7 @@ export const AgentBlock: BlockConfig<AgentResponse> = {
       type: 'slider',
       min: 0,
       max: 2,
-      defaultValue: 1,
+      defaultValue: 0.3,
       condition: () => ({
         field: 'model',
         value: (() => {
@@ -383,7 +384,7 @@ Example 3 (Array Input):
     ],
     config: {
       tool: (params: Record<string, any>) => {
-        const model = params.model || 'gpt-4o'
+        const model = params.model || 'claude-sonnet-4-5'
         if (!model) {
           throw new Error('No model selected')
         }
diff --git a/apps/sim/executor/consts.ts b/apps/sim/executor/consts.ts
index 95a06ad642..a31bed2bec 100644
--- a/apps/sim/executor/consts.ts
+++ b/apps/sim/executor/consts.ts
@@ -157,7 +157,7 @@ export const HTTP = {
 } as const
 
 export const AGENT = {
-  DEFAULT_MODEL: 'gpt-4o',
+  DEFAULT_MODEL: 'claude-sonnet-4-5',
   DEFAULT_FUNCTION_TIMEOUT: 5000,
   REQUEST_TIMEOUT: 120000,
   CUSTOM_TOOL_PREFIX: 'custom_',