diff --git a/client-html/index.html b/client-html/index.html
index ca7c412..2e92ce9 100644
--- a/client-html/index.html
+++ b/client-html/index.html
@@ -30,7 +30,7 @@ <h2>📡 Agent Connection</h2>
                 <div>
                     <label for="serverUrl">Server URL:</label>
                     <input type="text" id="serverUrl" placeholder="e.g., http://localhost:3000 or https://your-server.run.app"
-                    value="https://agentic-direct-server-hwgrypmndq-uk.a.run.app">
+                    value="http://localhost:3000/">
                     <button id="connectBtn" class="btn btn-primary">Connect</button>
                 </div>
                 <small class="help-text">💡 Enter only the base URL. The agent path (/a2a/buyer or /a2a/seller) will be added automatically.</small>
@@ -58,7 +58,7 @@ <h2>💬 Chat</h2>
             <div class="quick-actions">
                 <h3>Quick Actions:</h3>
                 <button class="btn btn-secondary quick-btn" data-message="create account for Nike">Create Account</button>
-                <button class="btn btn-secondary quick-btn" data-message="search products">Search Products</button>
+                <button class="btn btn-secondary quick-btn" data-message="Search Products Mock">Search Products Mock</button>
                 <button class="btn btn-secondary quick-btn" data-message="list products">List Products</button>
                 <button class="btn btn-secondary quick-btn" data-message="create order">Create Order</button>
             </div>
diff --git a/client/index.html b/client/index.html
index b210a0e..c3c51ba 100644
--- a/client/index.html
+++ b/client/index.html
@@ -28,7 +28,7 @@ <h2>📡 Agent Connection</h2>
 
             <div class="server-url">
                 <label for="serverUrl">Server URL:</label>
-                <input type="text" id="serverUrl" placeholder="e.g., http://localhost:3000 or https://your-server.run.app">
+                <input type="text" id="serverUrl" placeholder="e.g., http://localhost:3000 or https://your-server.run.app" value="http://localhost:3000/">
                 <button id="connectBtn" class="btn btn-primary">Connect</button>
             </div>
 
@@ -54,7 +54,7 @@ <h2>💬 Chat</h2>
             <div class="quick-actions">
                 <h3>Quick Actions:</h3>
                 <button class="btn btn-secondary quick-btn" data-message="create account for Nike">Create Account</button>
-                <button class="btn btn-secondary quick-btn" data-message="search products">Search Products</button>
+                <button class="btn btn-secondary quick-btn" data-message="Search Products Mock">Search Products Mock</button>
                 <button class="btn btn-secondary quick-btn" data-message="list products">List Products</button>
                 <button class="btn btn-secondary quick-btn" data-message="create order">Create Order</button>
             </div>
diff --git a/client/src/app.js b/client/src/app.js
index 8fa6aba..ad777b2 100644
--- a/client/src/app.js
+++ b/client/src/app.js
@@ -176,7 +176,7 @@ class A2ASDKClient {
             };
 
             // Send using official SDK client.sendMessage()
-            const response = await this.client.sendMessage(message);
+            const response = await this.client.sendMessage({ message });
 
             this.log('info', `📨 Response received from SDK`);
             console.log('Full SDK response:', response);
diff --git a/server/src/a2a/executor.ts b/server/src/a2a/executor.ts
index c48343b..1606c2e 100644
--- a/server/src/a2a/executor.ts
+++ b/server/src/a2a/executor.ts
@@ -10,6 +10,17 @@ import type { Message } from '@a2a-js/sdk';
 import type { MCPServer } from '../mcp/mcp-server.js';
 import type { MCPTool } from '../types/index.js';
 
+const DEFAULT_OPENAI_MODEL = 'gpt-4o-mini';
+const DEFAULT_OPENAI_REQUEST_CONFIG = {
+  temperature: 0.3
+};
+
+const OPENAI_MODEL_REQUEST_CONFIG: Record<string, Partial<typeof DEFAULT_OPENAI_REQUEST_CONFIG>> = {
+  'gpt-5': { temperature: 1 },
+  'gpt-5-mini': { temperature: 1 },
+  'gpt-5-nano': { temperature: 1 }
+};
+
 export class AgentExecutor implements IAgentExecutor {
   private openai: OpenAI;
   private mcpServer: MCPServer;
@@ -201,14 +212,20 @@ If the request requires only ONE tool, respond with this JSON format:
 
 Always return valid JSON.`;
 
+    const model = process.env.OPENAI_MODEL || DEFAULT_OPENAI_MODEL;
+    const modelConfig = {
+      ...DEFAULT_OPENAI_REQUEST_CONFIG,
+      ...OPENAI_MODEL_REQUEST_CONFIG[model]
+    };
+
     const response = await this.openai.chat.completions.create({
-      model: process.env.OPENAI_MODEL || 'gpt-4o-mini',
+      model,
       messages: [
         { role: 'system', content: systemPrompt },
         { role: 'user', content: userMessage }
       ],
       response_format: { type: 'json_object' },
-      temperature: 0.3
+      ...modelConfig
     });
 
     const content = response.choices[0]?.message?.content;