> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dottxt.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Zod

[Zod](https://zod.dev/) is the most common way to define schemas in TypeScript. The Vercel AI SDK accepts Zod schemas directly; no conversion step is needed.

## Install

```bash theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
npm install zod ai @ai-sdk/openai
```

## Basic usage

Pass a Zod schema to `generateObject`. The AI SDK converts it to JSON Schema and sends it to dottxt:

<CodeGroup>
  ```typescript Zod + AI SDK theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
  import { createOpenAI } from "@ai-sdk/openai";
  import { generateObject } from "ai";
  import { z } from "zod";

  const dottxt = createOpenAI({
    baseURL: "https://api.dottxt.ai/v1",
    apiKey: process.env.DOTTXT_API_KEY!,
  });

  const { object } = await generateObject({
    model: dottxt.chat("openai/gpt-oss-20b"),
    schema: z.object({
      name: z.string(),
      email: z.string(),
      role: z.string(),
    }),
    prompt: "Extract: John Smith <john@acme.com>, VP Engineering",
  });

  console.log(object.name);  // "John Smith"
  ```

  ```json JSON Schema (sent to API) theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
  {
    "type": "object",
    "properties": {
      "name": { "type": "string" },
      "email": { "type": "string" },
      "role": { "type": "string" }
    },
    "required": ["name", "email", "role"],
    "additionalProperties": false
  }
  ```
</CodeGroup>

The AI SDK adds `additionalProperties: false` automatically when converting Zod schemas.

## Adding constraints and descriptions

Zod's built-in methods translate to JSON Schema keywords. `.describe()` adds field-level descriptions that guide generation:

```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
const SupportTicket = z.object({
  category: z.enum(["billing", "account", "bug", "feature"])
    .describe("The area this ticket relates to."),
  priority: z.enum(["low", "medium", "high"])
    .describe("How urgently this ticket needs attention."),
  summary: z.string().min(10).max(500)
    .describe("A brief description of the issue."),
  confidence: z.number().min(0).max(1)
    .describe("How confident the model is in the classification."),
}).describe("A customer support ticket.");

const { object } = await generateObject({
  model: dottxt.chat("openai/gpt-oss-20b"),
  schema: SupportTicket,
  prompt: "Classify: I can't access my billing portal and it's blocking a renewal.",
});
```

## Streaming

Use `streamObject` to receive partial results as tokens stream in:

```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
import { streamObject } from "ai";

const { partialObjectStream } = streamObject({
  model: dottxt.chat("openai/gpt-oss-20b"),
  schema: z.object({
    title: z.string(),
    summary: z.string(),
    tags: z.array(z.string()).max(5),
  }),
  prompt: "Summarize: structured output improves LLM reliability...",
});

for await (const partial of partialObjectStream) {
  console.log(partial);
}
```

## Notes

* The AI SDK converts Zod schemas to JSON Schema before sending them to the API. To inspect the generated schema directly in Zod 4, use `z.toJSONSchema()`:

```typescript theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
console.log(JSON.stringify(z.toJSONSchema(SupportTicket), null, 2));
```