XML Agent

Some language models (like Anthropic's Claude) are particularly good at reasoning/writing XML. The below example shows how to use an agent that uses XML when prompting.

Setup

Install the Anthropic integration package, retrieve your key, and store it as an environment variable named ANTHROPIC_API_KEY:

tip

See this section for general instructions on installing integration packages.

npm

npm install @langchain/anthropic

Yarn

yarn add @langchain/anthropic

pnpm

pnpm add @langchain/anthropic

This demo also uses Tavily, but you can also swap in another built in tool. You'll need to sign up for an API key and set it as TAVILY_API_KEY.

Initialize Tools

We will first create a tool:

import { TavilySearchResults } from "@langchain/community/tools/tavily_search";

// Define the tools the agent will have access to.
const tools = [new TavilySearchResults({ maxResults: 1 })];

Create Agent

import { AgentExecutor, createXmlAgent } from "langchain/agents";
import { pull } from "langchain/hub";
import { ChatAnthropic } from "@langchain/anthropic";
import type { PromptTemplate } from "@langchain/core/prompts";

// Get the prompt to use - you can modify this!
// If you want to see the prompt in full, you can at:
// https://smith.langchain.com/hub/hwchase17/xml-agent-convo
const prompt = await pull<PromptTemplate>("hwchase17/xml-agent-convo");

const llm = new ChatAnthropic({
  temperature: 0,
});

const agent = await createXmlAgent({
  llm,
  tools,
  prompt,
});

Run Agent

Now, let's run our agent!

tip

LangSmith trace

const agentExecutor = new AgentExecutor({
  agent,
  tools,
});

const result = await agentExecutor.invoke({
  input: "what is LangChain?",
});

console.log(result);

/*
  {
    input: 'what is LangChain?',
    output: '\n' +
      'LangChain is a platform that links large language models like GPT-3.5 and GPT-4 to external data sources to build natural language processing (NLP) applications. It provides modules and integrations to help create NLP apps more easily across various industries and use cases. Some key capabilities LangChain offers include connecting to LLMs, integrating external data sources, and enabling the development of custom NLP solutions.\n'
  }
*/

Using with chat history

For more details, see this section of the agent quickstart.

const result2 = await agentExecutor.invoke({
  input: "what's my name?",
  // Notice that chat_history is a string, since this prompt is aimed at LLMs, not chat models
  chat_history: "Human: Hi! My name is Cob\nAI: Hello Cob! Nice to meet you",
});

console.log(result2);

/*
  {
    input: "what's my name?",
    chat_history: 'Human: Hi! My name is Cob\nAI: Hello Cob! Nice to meet you',
    output: 'Based on our previous conversation, your name is Cob.'
  }
*/