createAgent

import { createAgent, tool } from "langchain";
import { z } from "zod";

const search = tool(
  ({ query }) => `Results for: ${query}`,
  {
    name: "search",
    description: "Search for information",
    schema: z.object({
      query: z.string().describe("The search query"),
    })
  }
);

const agent = createAgent({
  llm: "openai:gpt-4o",
  tools: [search],
});

const result = await agent.invoke({
  messages: [{ role: "user", content: "Search for ReAct agents" }],
});

import { createAgent } from "langchain";
import { z } from "zod";

const ContactInfo = z.object({
  name: z.string(),
  email: z.string(),
  phone: z.string(),
});

const agent = createAgent({
  llm: "openai:gpt-4o",
  tools: [],
  responseFormat: ContactInfo,
});

const result = await agent.invoke({
  messages: [{
    role: "user",
    content: "Extract: John Doe, john@example.com, (555) 123-4567"
  }],
});

console.log(result.structuredResponse);
// { name: 'John Doe', email: 'john@example.com', phone: '(555) 123-4567' }

const stream = await agent.stream(
  { messages: [{ role: "user", content: "What's the weather?" }] },
  { streamMode: "values" }
);

for await (const chunk of stream) {
  // ...
}

import { createAgent } from "langchain";
import { StateSchema, ReducedValue } from "@langchain/langgraph";
import { z } from "zod";

const AgentState = new StateSchema({
  userId: z.string(),
  count: z.number().default(0),
  history: new ReducedValue(
    z.array(z.string()).default(() => []),
    { inputSchema: z.string(), reducer: (c, n) => [...c, n] }
  ),
});

const agent = createAgent({
  model: "openai:gpt-4o",
  tools: [searchTool],
  stateSchema: AgentState,
});