andAgent

Add AI to your workflow. Get structured, typed responses from language models.

Quick Start

import { createWorkflowChain, Agent } from "@voltagent/core";
import { z } from "zod";
import { openai } from "@ai-sdk/openai";

// Create an agent
const agent = new Agent({
  name: "Assistant",
  // Pass an ai-sdk model directly
  model: openai("gpt-4o-mini"),
  instructions: "Be concise and helpful",
});

// Use it in a workflow
const workflow = createWorkflowChain({
  id: "analyze-text",
  input: z.object({ text: z.string() }),
}).andAgent(({ data }) => `Analyze this text: ${data.text}`, agent, {
  schema: z.object({
    sentiment: z.enum(["positive", "negative", "neutral"]),
    summary: z.string(),
  }),
});

const result = await workflow.run({ text: "I love this!" });
// Result: { sentiment: "positive", summary: "Expression of enthusiasm" }

How It Works

andAgent = AI prompt + structured output schema:

.andAgent(
  prompt,    // What to ask the AI
  agent,     // Which AI to use
  { schema } // What shape the answer should be
)

Important: andAgent uses generateText with Output.object under the hood, which means:

• ✅ You get structured, typed responses based on your schema
• ✅ The agent can use tools during this step
• ❌ Streaming is not supported (response returns when complete)

Need streaming or custom tool handling? Use andThen to call the agent directly with streamText or generateText.

Function Signature

// Simple prompt (string)
.andAgent("Summarize this", agent, { schema })

// Dynamic prompt from data (string)
.andAgent(({ data }) => `Analyze: ${data.text}`, agent, { schema })

// Advanced: pass ai-sdk v5 ModelMessage[] (multimodal)
.andAgent(
  ({ data }) => [
    { role: 'user', content: [{ type: 'text', text: `Hello ${data.name}` }] },
  ],
  agent,
  { schema }
)

// Advanced: pass UIMessage[]
.andAgent(
  ({ data }) => [
    { id: crypto.randomUUID(), role: 'user', parts: [{ type: 'text', text: data.prompt }] },
  ],
  agent,
  { schema }
)

Common Patterns

Text Analysis

.andAgent(
  ({ data }) => `Analyze sentiment of: ${data.review}`,
  agent,
  {
    schema: z.object({
      sentiment: z.enum(["positive", "negative", "neutral"]),
      score: z.number().min(0).max(1),
      keywords: z.array(z.string())
    })
  }
)

Content Generation

.andAgent(
  ({ data }) => `Write a ${data.tone} email about ${data.topic}`,
  agent,
  {
    schema: z.object({
      subject: z.string(),
      body: z.string(),
      suggestedSendTime: z.string()
    })
  }
)

Data Extraction

.andAgent(
  ({ data }) => `Extract key information from: ${data.document}`,
  agent,
  {
    schema: z.object({
      people: z.array(z.string()),
      dates: z.array(z.string()),
      locations: z.array(z.string()),
      mainTopic: z.string()
    })
  }
)

Dynamic Prompts

Build prompts from workflow data:

.andAgent(
  ({ data }) => {
    // Adjust prompt based on data
    if (data.userLevel === "beginner") {
      return `Explain in simple terms: ${data.question}`;
    }
    return `Provide technical details about: ${data.question}`;
  },
  agent,
  { schema: z.object({ answer: z.string() }) }
)

Chaining with Other Steps

Combine AI with logic:

createWorkflowChain({ id: "smart-email" })
  // Step 1: Classify with AI
  .andAgent(({ data }) => `What type of email is this: ${data.email}`, agent, {
    schema: z.object({
      type: z.enum(["support", "sales", "spam"]),
      priority: z.enum(["low", "medium", "high"]),
    }),
  })
  // Step 2: Route based on classification
  .andThen({
    id: "route-email",
    execute: async ({ data }) => {
      if (data.type === "spam") {
        return { action: "delete" };
      }
      return {
        action: "forward",
        to: data.type === "support" ? "support@" : "sales@",
      };
    },
  });

Streaming or Custom Tool Handling

andAgent supports tools, but it only returns the structured output when the step completes. Use andThen when you need streaming tokens or to inspect tool calls/results directly:

import { Agent, createTool } from "@voltagent/core";
import { z } from "zod";
import { openai } from "@ai-sdk/openai";

const getWeatherTool = createTool({
  name: "get_weather",
  description: "Get weather for a location",
  parameters: z.object({ city: z.string() }),
  execute: async ({ city }) => {
    return { temp: 72, condition: "sunny" };
  },
});

const agent = new Agent({
  name: "Assistant",
  model: openai("gpt-4o-mini"),
  tools: [getWeatherTool],
});

// Use andThen to call the agent directly when you need streaming or tool call inspection
createWorkflowChain({ id: "weather-flow" }).andThen({
  id: "get-weather",
  execute: async ({ data }) => {
    // Call streamText/generateText directly for streaming or tool call handling
    const result = await agent.generateText(`What's the weather in ${data.city}?`);
    return { response: result.text };
  },
});

Best Practices

1. Keep prompts clear - AI performs better with specific instructions
2. Use enums for categories - z.enum() ensures valid options
3. Add descriptions to schema fields - Helps AI understand what you want
4. Handle edge cases - Check for missing or low-confidence results
5. Need streaming or tool inspection? - Use andThen with direct agent calls instead of andAgent

Next Steps

• Learn about andWhen for conditional logic
• Explore andAll to run multiple agents in parallel
• See andThen to process AI outputs
• Execute workflows via REST API