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Subscribing to events

You can subscribe to a number of events that are emitted by the Agent and the underlying tools, chains and models via callbacks.

For more info on the events available see the Callbacks section of the docs.

tip

See this section for general instructions on installing integration packages.

npm install @langchain/openai
import { initializeAgentExecutorWithOptions } from "langchain/agents";
import { OpenAI } from "@langchain/openai";
import { Calculator } from "@langchain/community/tools/calculator";
import { SerpAPI } from "@langchain/community/tools/serpapi";

const model = new OpenAI({ temperature: 0 });
const tools = [
  new SerpAPI(process.env.SERPAPI_API_KEY, {
    location: "Austin,Texas,United States",
    hl: "en",
    gl: "us",
  }),
  new Calculator(),
];
const executor = await initializeAgentExecutorWithOptions(tools, model, {
  agentType: "zero-shot-react-description",
});

const input = `Who is Olivia Wilde's boyfriend? What is his current age raised to the 0.23 power?`;
const result = await executor.invoke(
  { input },
  {
    callbacks: [
      {
        handleAgentAction(action, runId) {
          console.log("\nhandleAgentAction", action, runId);
        },
        handleAgentEnd(action, runId) {
          console.log("\nhandleAgentEnd", action, runId);
        },
        handleToolEnd(output, runId) {
          console.log("\nhandleToolEnd", output, runId);
        },
      },
    ],
  }
);
/*
handleAgentAction {
  tool: 'search',
  toolInput: 'Olivia Wilde boyfriend',
  log: " I need to find out who Olivia Wilde's boyfriend is and then calculate his age raised to the 0.23 power.\n" +
    'Action: search\n' +
    'Action Input: "Olivia Wilde boyfriend"'
} 9b978461-1f6f-4d5f-80cf-5b229ce181b6

handleToolEnd In January 2021, Wilde began dating singer Harry Styles after meeting during the filming of Don't Worry Darling. Their relationship ended in November 2022. 062fef47-8ad1-4729-9949-a57be252e002

handleAgentAction {
  tool: 'search',
  toolInput: 'Harry Styles age',
  log: " I need to find out Harry Styles' age.\n" +
    'Action: search\n' +
    'Action Input: "Harry Styles age"'
} 9b978461-1f6f-4d5f-80cf-5b229ce181b6

handleToolEnd 29 years 9ec91e41-2fbf-4de0-85b6-12b3e6b3784e 61d77e10-c119-435d-a985-1f9d45f0ef08

handleAgentAction {
  tool: 'calculator',
  toolInput: '29^0.23',
  log: ' I need to calculate 29 raised to the 0.23 power.\n' +
    'Action: calculator\n' +
    'Action Input: 29^0.23'
} 9b978461-1f6f-4d5f-80cf-5b229ce181b6

handleToolEnd 2.169459462491557 07aec96a-ce19-4425-b863-2eae39db8199

handleAgentEnd {
  returnValues: {
    output: "Harry Styles is Olivia Wilde's boyfriend and his current age raised to the 0.23 power is 2.169459462491557."
  },
  log: ' I now know the final answer.\n' +
    "Final Answer: Harry Styles is Olivia Wilde's boyfriend and his current age raised to the 0.23 power is 2.169459462491557."
} 9b978461-1f6f-4d5f-80cf-5b229ce181b6
*/

console.log({ result });
// { result: "Harry Styles is Olivia Wilde's boyfriend and his current age raised to the 0.23 power is 2.169459462491557." }

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