diff --git a/mcp-client-typescript/index.ts b/mcp-client-typescript/index.ts
index b7d578c..99a185b 100644
--- a/mcp-client-typescript/index.ts
+++ b/mcp-client-typescript/index.ts
@@ -12,6 +12,7 @@ import dotenv from "dotenv";
 
 dotenv.config(); // load environment variables from .env
 
+const ANTHROPIC_MODEL = "claude-sonnet-4-5";
 const ANTHROPIC_API_KEY = process.env.ANTHROPIC_API_KEY;
 if (!ANTHROPIC_API_KEY) {
   throw new Error("ANTHROPIC_API_KEY is not set");
@@ -92,7 +93,7 @@ class MCPClient {
 
     // Initial Claude API call
     const response = await this.anthropic.messages.create({
-      model: "claude-sonnet-4-5",
+      model: ANTHROPIC_MODEL,
       max_tokens: 1000,
       messages,
       tools: this.tools,
@@ -125,7 +126,7 @@ class MCPClient {
 
         // Get next response from Claude
         const response = await this.anthropic.messages.create({
-          model: "claude-sonnet-4-5",
+          model: ANTHROPIC_MODEL,
           max_tokens: 1000,
           messages,
         });