Langchain.js

npm install --save @arizeai/openinference-instrumentation-langchain \  @arizeai/phoenix-otel

import { register } from "@arizeai/phoenix-otel";import { LangChainInstrumentation } from "@arizeai/openinference-instrumentation-langchain";import * as CallbackManagerModule from "@langchain/core/callbacks/manager";const provider = register({  projectName: "langchain-app",});const lcInstrumentation = new LangChainInstrumentation();// LangChain must be manually instrumented as it doesn't have // a traditional module structurelcInstrumentation.manuallyInstrument(CallbackManagerModule);

import * as z from "zod";// npm install @langchain/anthropic to call the modelimport { createAgent, tool } from "langchain";const getWeather = tool(  ({ city }) => `It's always sunny in ${city}!`,  {    name: "get_weather",    description: "Get the weather for a given city",    schema: z.object({      city: z.string(),    }),  },);const agent = createAgent({  model: "claude-sonnet-4-5-20250929",  tools: [getWeather],});console.log(  await agent.invoke({    messages: [{ role: "user", content: "What's the weather in Tokyo?" }],  }));