Quickstart

Build a tool-using agent in under 5 minutes.

This guide covers the three patterns you’ll use most: plain chat, tools, and streaming.

---

1. Plain chat (no tools)

import { Agent, createAnthropicProvider } from "kenpachi";

const provider = createAnthropicProvider({
  apiKey: process.env.ANTHROPIC_API_KEY!,
  model: "claude-sonnet-4-6",
});
const agent = new Agent(provider, []);

const result = await agent.run("Write a one-sentence greeting.");
console.log(result.text);

agent.run() loops until the model stops calling tools and returns final text. For chat-only agents, pass an empty tools array.

---

2. Agent with a tool

Define a tool with defineTool, pass it to the agent, and ask a question that requires it:

import { z } from "zod";
import { Agent, defineTool, createAnthropicProvider } from "kenpachi";

const getWeather = defineTool({
  name: "get_weather",
  description: "Get current weather for a city",
  schema: z.object({
    city: z.string().describe("City name"),
  }),
  async execute({ city }) {
    // Replace with your real API call
    return { city, tempC: 24, condition: "sunny" };
  },
});

const provider = createAnthropicProvider({
  apiKey: process.env.ANTHROPIC_API_KEY!,
  model: "claude-sonnet-4-6",
});
const agent = new Agent(provider, [getWeather]);

const result = await agent.run("What's the weather in Nashik?");
console.log(result.text);
// → "It's sunny and 24°C in Nashik."

kenpachi handles the full loop: model calls get_weather → your execute runs → result goes back to the model → model writes the final answer.

---

3. Stream text to your UI

Add onText to show tokens as they arrive:

process.stdout.write("Agent: ");

const result = await agent.run("Tell me a fun fact about Nashik", {
  onText: (chunk) => process.stdout.write(chunk),
});

process.stdout.write("\n");

See Streaming for the full event API (agent.stream()).

---

What’s next?

Handoffs

Delegate to billing, support, or other specialist agents.

Time-travel context

Undo, edit, or branch conversations without extra API cost.

Schema Validation & Coercion

Recover when the model sends bad tool arguments.

Agent API

Full reference for run(), stream(), and options.