# Call Tools in Parallel

Some language models support calling tools in parallel. This is particularly useful when multiple tools are independent of each other and can be executed in parallel during the same generation step.

<Browser>
  <ChatGeneration
    history={[
      { role: 'User', content: 'How is it going?' },
      { role: 'Assistant', content: 'All good, how may I help you?' },
    ]}
    inputMessage={{
      role: 'User',
      content: 'What is the weather in Paris and New York?',
    }}
    outputMessage={{
      role: 'Assistant',
      content:
        'The weather is 24°C in New York and 25°C in Paris. It is sunny in both cities.',
    }}
  />
</Browser>

## Client

Let's create a React component that imports the `useChat` hook from the `@ai-sdk/react` module. The `useChat` hook will call the `/api/chat` endpoint when the user sends a message. The endpoint will generate the assistant's response based on the conversation history and stream it to the client. If the assistant responds with a tool call, the hook will automatically display them as well.

You will use the `maxSteps` to specify the maximum number of steps that can made before the model or the user responds with a text message. In this example, you will set it to `2` to allow for another call with the tool result to happen.

```tsx filename='app/page.tsx'
'use client';

import { useChat } from '@ai-sdk/react';

export default function Page() {
  const { messages, input, setInput, append } = useChat({
    api: '/api/chat',
    maxSteps: 2,
  });

  return (
    <div>
      <input
        value={input}
        onChange={event => {
          setInput(event.target.value);
        }}
        onKeyDown={async event => {
          if (event.key === 'Enter') {
            append({ content: input, role: 'user' });
          }
        }}
      />

      {messages.map((message, index) => (
        <div key={index}>{message.content}</div>
      ))}
    </div>
  );
}
```

## Server

You will create a new route at `/api/chat` that will use the `streamText` function from the `ai` module to generate the assistant's response based on the conversation history.

You will use the [`tools`](/docs/reference/ai-sdk-core/generate-text#tools) parameter to specify a tool called `getWeather` that will get the weather for a location.

You will add the `getWeather` function and use zod to specify the schema for its parameters.

```ts filename='app/api/chat/route.ts'
import { ToolInvocation, streamText } from 'ai';
import { openai } from '@ai-sdk/openai';
import { z } from 'zod';

interface Message {
  role: 'user' | 'assistant';
  content: string;
  toolInvocations?: ToolInvocation[];
}

function getWeather({ city, unit }) {
  return { value: 25, description: 'Sunny' };
}

export async function POST(req: Request) {
  const { messages }: { messages: Message[] } = await req.json();

  const result = streamText({
    model: openai('gpt-4o'),
    system: 'You are a helpful assistant.',
    messages,
    tools: {
      getWeather: {
        description: 'Get the weather for a location',
        parameters: z.object({
          city: z.string().describe('The city to get the weather for'),
          unit: z
            .enum(['C', 'F'])
            .describe('The unit to display the temperature in'),
        }),
        execute: async ({ city, unit }) => {
          const { value, description } = getWeather({ city, unit });
          return `It is currently ${value}°${unit} and ${description} in ${city}!`;
        },
      },
    },
  });

  return result.toDataStreamResponse();
}
```

---

<GithubLink link="https://github.com/vercel/ai/blob/main/examples/next-openai-pages/pages/tools/call-tools-in-parallel/index.tsx" />


## Navigation

- [Generate Text](/v4/cookbook/next/generate-text)
- [Generate Text with Chat Prompt](/v4/cookbook/next/generate-text-with-chat-prompt)
- [Generate Image with Chat Prompt](/v4/cookbook/next/generate-image-with-chat-prompt)
- [Stream Assistant Response](/v4/cookbook/next/stream-assistant-response)
- [Stream Assistant Response with Tools](/v4/cookbook/next/stream-assistant-response-with-tools)
- [Caching Middleware](/v4/cookbook/next/caching-middleware)
- [Stream Text](/v4/cookbook/next/stream-text)
- [Stream Text with Chat Prompt](/v4/cookbook/next/stream-text-with-chat-prompt)
- [Stream Text with Image Prompt](/v4/cookbook/next/stream-text-with-image-prompt)
- [Chat with PDFs](/v4/cookbook/next/chat-with-pdf)
- [streamText Multi-Step Cookbook](/v4/cookbook/next/stream-text-multistep)
- [Markdown Chatbot with Memoization](/v4/cookbook/next/markdown-chatbot-with-memoization)
- [Generate Object](/v4/cookbook/next/generate-object)
- [Generate Object with File Prompt through Form Submission](/v4/cookbook/next/generate-object-with-file-prompt)
- [Stream Object](/v4/cookbook/next/stream-object)
- [Call Tools](/v4/cookbook/next/call-tools)
- [Call Tools in Parallel](/v4/cookbook/next/call-tools-in-parallel)
- [Call Tools in Multiple Steps](/v4/cookbook/next/call-tools-multiple-steps)
- [Model Context Protocol (MCP) Tools](/v4/cookbook/next/mcp-tools)
- [Human-in-the-Loop with Next.js](/v4/cookbook/next/human-in-the-loop)
- [Send Custom Body from useChat](/v4/cookbook/next/send-custom-body-from-use-chat)
- [Render Visual Interface in Chat](/v4/cookbook/next/render-visual-interface-in-chat)


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