diff --git a/docs/core_docs/docs/integrations/chat/anthropic.ipynb b/docs/core_docs/docs/integrations/chat/anthropic.ipynb
index 4786d1f68a9b..9fafc787406e 100644
--- a/docs/core_docs/docs/integrations/chat/anthropic.ipynb
+++ b/docs/core_docs/docs/integrations/chat/anthropic.ipynb
@@ -953,7 +953,7 @@
     "const customClient = new AnthropicVertex();\n",
     "\n",
     "const modelWithCustomClient = new ChatAnthropic({\n",
-    "  modelName: \"claude-3-sonnet-20240229\",\n",
+    "  modelName: \"claude-3-sonnet@20240229\",\n",
     "  maxRetries: 0,\n",
     "  createClient: () => customClient,\n",
     "});\n",
diff --git a/libs/langchain-anthropic/src/chat_models.ts b/libs/langchain-anthropic/src/chat_models.ts
index c8edf3c17d0d..1e8853ff5b8a 100644
--- a/libs/langchain-anthropic/src/chat_models.ts
+++ b/libs/langchain-anthropic/src/chat_models.ts
@@ -633,7 +633,7 @@ export class ChatAnthropicMessages<
       fields?.anthropicApiKey ??
       getEnvironmentVariable("ANTHROPIC_API_KEY");
 
-    if (!this.anthropicApiKey) {
+    if (!this.anthropicApiKey && !fields?.createClient) {
       throw new Error("Anthropic API key not found");
     }
     this.clientOptions = fields?.clientOptions ?? {};
@@ -949,9 +949,6 @@ export class ChatAnthropicMessages<
   ): Promise<Anthropic.Message> {
     if (!this.batchClient) {
       const options = this.apiUrl ? { baseURL: this.apiUrl } : undefined;
-      if (!this.apiKey) {
-        throw new Error("Missing Anthropic API key.");
-      }
       this.batchClient = this.createClient({
         ...this.clientOptions,
         ...options,