diff --git a/src/index.ts b/src/index.ts
index 58edb4d..0f7599d 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,27 +1,45 @@
 import { SwapApi } from "../generated/apis/SwapApi";
 import { ConfigurationParameters, Configuration } from "../generated/runtime";
 
-// Define server URLs
-const PUBLIC_SERVER_URL = "https://lite-api.jup.ag/swap/v1";
-const API_KEY_SERVER_URL = "https://api.jup.ag/swap/v1";
+// --- Configuration Constants ---
+
+// Public endpoint URL for the Jupiter Swap API (does not require an API key).
+const PUBLIC_API_URL: string = "https://lite-api.jup.ag/swap/v1";
+
+// Dedicated endpoint URL for API key users (often offers higher rate limits or premium features).
+const AUTHENTICATED_API_URL: string = "https://api.jup.ag/swap/v1";
 
 /**
- * Creates a Jupiter API client with optional API key support
- * @param config Configuration parameters
- * @returns SwapApi instance
+ * Creates a configured Jupiter API client instance (SwapApi).
+ * * The client automatically switches the base URL and adds the 'x-api-key' header
+ * if an API key is provided in the configuration.
+ * * @param config Optional configuration parameters, including 'apiKey'.
+ * @returns A new instance of SwapApi ready for use.
  */
-export const createJupiterApiClient = (config?: ConfigurationParameters) => {
-  // Determine which server URL to use based on whether an API key is provided
-  const hasApiKey = config?.apiKey !== undefined;
+export const createJupiterApiClient = (config?: ConfigurationParameters): SwapApi => {
+  // Check if an API key is explicitly provided and is a non-empty string.
+  const apiKey = config?.apiKey;
+  const hasValidApiKey = typeof apiKey === 'string' && apiKey.length > 0;
+  
+  // Determine the appropriate base path and headers based on the presence of an API key.
+  const basePath = hasValidApiKey ? AUTHENTICATED_API_URL : PUBLIC_API_URL;
   
-  // Create a new configuration with the appropriate base path
-  const configWithServer: ConfigurationParameters = {
+  const headers = hasValidApiKey 
+    ? { 'x-api-key': apiKey as string } // Safely assert apiKey as string here
+    : undefined;
+
+  // Create the final configuration object.
+  const finalConfig: ConfigurationParameters = {
     ...config,
-    basePath: hasApiKey ? API_KEY_SERVER_URL : PUBLIC_SERVER_URL,
-    headers: hasApiKey ? { 'x-api-key': config?.apiKey as string } : undefined
+    basePath: basePath,
+    headers: headers,
+    // Note: apiKey field might be kept in config for internal library use, 
+    // but the actual header is manually constructed above.
   };
-  
-  return new SwapApi(new Configuration(configWithServer));
+
+  // Instantiate and return the API client.
+  return new SwapApi(new Configuration(finalConfig));
 };
 
+// Re-export all type and interface definitions generated by the OpenAPI tool.
 export * from "../generated";