diff --git a/.env.example b/.env.example
index 5d766dc..5820dd3 100644
--- a/.env.example
+++ b/.env.example
@@ -23,6 +23,12 @@ OPENAI_API_KEY="" # sk-90...
 # You can get this at aistudio.google.com
 GOOGLE_API_KEY="" # AIz...
 
+# ------------------------------
+# Obligatory if you're using Anthropic's models and want to use tool calling:
+# ------------------------------
+# You can get this at https://anthropic.com/
+ANTHROPIC_API_KEY="" # sk-...
+
 # ------------------------------
 # Obligatory if you're using one of OpenRouter models:
 # ------------------------------
diff --git a/src/clients/open-router.ts b/src/clients/open-router.ts
index 0511663..5239ab0 100644
--- a/src/clients/open-router.ts
+++ b/src/clients/open-router.ts
@@ -14,6 +14,7 @@ import {
   ConversationSummaryMemory,
 } from "langchain/memory";
 import {
+  ANTHROPIC_API_KEY,
   DEFAULT_MODEL,
   GOOGLE_API_KEY,
   MODEL_TEMPERATURE,
@@ -29,10 +30,12 @@ import {
   getOpenRouterMemoryFor,
 } from "../crud/conversation";
 import {
+  anthropicToolCallingModels,
   googleToolCallingModels,
   openAIToolCallingModels,
 } from "./tools/tool-calling-models";
 import { tools } from "./tools/tools-openrouter";
+import { ChatAnthropic } from "@langchain/anthropic";
 
 function parseMessageHistory(
   rawHistory: { [key: string]: string }[]
@@ -160,6 +163,29 @@ export async function createExecutorForOpenRouter(
       prompt,
     });
   }
+  // Anthropics LLM with Tool Calling Agent
+  else if (
+    anthropicToolCallingModels.includes(llmModel) &&
+    ANTHROPIC_API_KEY !== ""
+  ) {
+    console.log("Using Anthropics LLM");
+    prompt = await pull<ChatPromptTemplate>(
+      "luisotee/wa-assistant-tool-calling"
+    );
+
+    llm = new ChatAnthropic({
+      modelName: llmModel,
+      streaming: true,
+      temperature: MODEL_TEMPERATURE,
+      apiKey: ANTHROPIC_API_KEY,
+    });
+
+    agent = await createToolCallingAgent({
+      llm,
+      tools,
+      prompt,
+    });
+  }
   // OpenRouter LLMs without Tool Calling Agent, with Structured Agent
   else {
     console.log("Using OpenRouter LLM");
diff --git a/src/clients/tools/tool-calling-models.ts b/src/clients/tools/tool-calling-models.ts
index c7b4981..3043072 100644
--- a/src/clients/tools/tool-calling-models.ts
+++ b/src/clients/tools/tool-calling-models.ts
@@ -6,3 +6,10 @@ export const openAIToolCallingModels = [
 ];
 
 export const googleToolCallingModels = ["gemini-1.5-pro", "gemini-1.5-flash"];
+
+export const anthropicToolCallingModels = [
+  "claude-3-5-sonnet-20240620",
+  "claude-3-opus-20240229",
+  "claude-3-sonnet-20240229",
+  "claude-3-haiku-20240307",
+];
diff --git a/src/constants.ts b/src/constants.ts
index 99db14e..56655bd 100644
--- a/src/constants.ts
+++ b/src/constants.ts
@@ -64,3 +64,4 @@ export const MODEL_TEMPERATURE = parseFloat(
 );
 export const ENABLE_GOOGLE_ROUTES = process.env.ENABLE_GOOGLE_ROUTES as string;
 export const GOOGLE_API_KEY = process.env.GOOGLE_API_KEY as string;
+export const ANTHROPIC_API_KEY = process.env.ANTHROPIC_API_KEY as string;
diff --git a/src/handlers/command/change-llm.ts b/src/handlers/command/change-llm.ts
index 3ec0fc8..418e31e 100644
--- a/src/handlers/command/change-llm.ts
+++ b/src/handlers/command/change-llm.ts
@@ -12,7 +12,9 @@ const LLM_OPTIONS = {
   "5": "o1-mini",
   "6": "gemini-1.5-pro",
   "7": "gemini-1.5-flash",
-  "8": "anthropic/claude-3.5-sonnet",
+  "8": "claude-3-5-sonnet-20240620",
+  "9": "claude-3-opus-20240229",
+  "10": "claude-3-haiku-20240307",
 };
 
 export async function handleChangeLLM(message: Message, args: string) {
@@ -38,13 +40,15 @@ export async function handleChangeLLM(message: Message, args: string) {
   *${CMD_PREFIX}change 3* for _gpt-4o_ (OpenAI API)
   *${CMD_PREFIX}change 4* for _o1-preview_ (OpenAI API)
   *${CMD_PREFIX}change 5* for _o1-mini_ (OpenAI API)
-  *${CMD_PREFIX}change 6* for _gemini-pro-1.5_ (Google API)
+  *${CMD_PREFIX}change 6* for _gemini-1.5-pro_ (Google API)
   *${CMD_PREFIX}change 7* for _gemini-1.5-flash_ (Google API)
-  *${CMD_PREFIX}change 8* for _anthropic/claude-3.5-sonnet_ (OpenRouter API)
+  *${CMD_PREFIX}change 8* for _claude-3-5-sonnet_ (Anthropic API)
+  *${CMD_PREFIX}change 9* for _claude-3-opus_ (Anthropic API)
+  *${CMD_PREFIX}change 10* for _claude-3-haiku_ (Anthropic API)
 
-  You can also type the name of your desired model, like *${CMD_PREFIX}change mistralai/mixtral-8x7b-instruct*
+  You can also type the name of your desired model supported by OpenRouter, like *${CMD_PREFIX}change mistralai/mixtral-8x7b-instruct*
 
-  See the list of available models at OpenRouter docs in https://openrouter.ai/docs#models.
+  See the list of available models of OpenRouter docs in https://openrouter.ai/docs#models.
 `,
       chat.id._serialized,
       { linkPreview: false }