# How to build an AI chef assistant

In this guide, you'll create a "Chef Assistant" agent that helps users cook meals with available ingredients.

You'll learn how to create the agent and register it with Mastra. Next, you'll interact with the agent through your terminal and get to know different response formats. Lastly, you'll access the agent through Mastra's local API endpoints.

[YouTube video player](https://www.youtube-nocookie.com/embed/_tZhOqHCrF0)

## Prerequisites

- Node.js `v22.13.0` or later installed
- An API key from a supported [Model Provider](https://mastra.ai/models)
- An existing Mastra project (Follow the [installation guide](https://mastra.ai/guides/getting-started/quickstart) to set up a new project)

## Create the agent

To create an agent in Mastra use the `Agent` class to define it and then register it with Mastra.

1. Create a new file `src/mastra/agents/chefAgent.ts` and define your agent:

   ```ts
   import { Agent } from '@mastra/core/agent'

   export const chefAgent = new Agent({
     id: 'chef-agent',
     name: 'chef-agent',
     instructions:
       'You are Michel, a practical and experienced home chef' +
       'You help people cook with whatever ingredients they have available.',
     model: 'openai/gpt-5.4',
   })
   ```

2. In your `src/mastra/index.ts` file, register the agent:

   ```ts
   import { Mastra } from '@mastra/core'
   import { chefAgent } from './agents/chefAgent'

   export const mastra = new Mastra({
     agents: { chefAgent },
   })
   ```

## Interact with the agent

Depending on your requirements you can interact and get responses from the agent in different formats. In the following steps you'll learn how to generate, stream, and get structured output.

1. Create a new file `src/index.ts` and add a `main()` function to it. Inside, craft a query to ask the agent and log its response.

   ```ts
   import { chefAgent } from './mastra/agents/chefAgent'

   async function main() {
     const query =
       'In my kitchen I have: pasta, canned tomatoes, garlic, olive oil, and some dried herbs (basil and oregano). What can I make?'
     console.log(`Query: ${query}`)

     const response = await chefAgent.generate([{ role: 'user', content: query }])
     console.log('\n👨‍🍳 Chef Michel:', response.text)
   }

   main()
   ```

   Afterwards, run the script:

   ```bash
   npx bun src/index.ts
   ```

   You should get an output similar to this:

   ```text
   Query: In my kitchen I have: pasta, canned tomatoes, garlic, olive oil, and some dried herbs (basil and oregano). What can I make?

   👨‍🍳 Chef Michel: You can make a delicious pasta al pomodoro! Here's how...
   ```

2. In the previous example you might have waited a bit for the response without any sign of progress. To show the agent's output as it creates it you should instead stream its response to the terminal.

   ```ts
   import { chefAgent } from './mastra/agents/chefAgent'

   async function main() {
     const query =
       "Now I'm over at my friend's house, and they have: chicken thighs, coconut milk, sweet potatoes, and some curry powder."
     console.log(`Query: ${query}`)

     const stream = await chefAgent.stream([{ role: 'user', content: query }])

     console.log('\n Chef Michel: ')

     for await (const chunk of stream.textStream) {
       process.stdout.write(chunk)
     }

     console.log('\n\n✅ Recipe complete!')
   }

   main()
   ```

   Afterwards, run the script again:

   ```bash
   npx bun src/index.ts
   ```

   You should get an output similar to the one below. This time though you can read it line by line instead of one large block.

   ```text
   Query: Now I'm over at my friend's house, and they have: chicken thighs, coconut milk, sweet potatoes, and some curry powder.

   👨‍🍳 Chef Michel:
   Great! You can make a comforting chicken curry...

   ✅ Recipe complete!
   ```

3. Instead of showing the agent's response to a human you might want to pass it along to another part of your code. For these instances your agent should return [structured output](https://mastra.ai/docs/agents/structured-output).

   Change your `src/index.ts` to the following:

   ```ts
   import { chefAgent } from './mastra/agents/chefAgent'
   import { z } from 'zod'

   async function main() {
     const query = 'I want to make lasagna, can you generate a lasagna recipe for me?'
     console.log(`Query: ${query}`)

     // Define the Zod schema
     const schema = z.object({
       ingredients: z.array(
         z.object({
           name: z.string(),
           amount: z.string(),
         }),
       ),
       steps: z.array(z.string()),
     })

     const response = await chefAgent.generate([{ role: 'user', content: query }], {
       structuredOutput: {
         schema,
       },
     })
     console.log('\n👨‍🍳 Chef Michel:', response.object)
   }

   main()
   ```

   After running the script again you should get an output similar to this:

   ```text
   Query: I want to make lasagna, can you generate a lasagna recipe for me?

   👨‍🍳 Chef Michel: {
     ingredients: [
       { name: "Lasagna noodles", amount: "12 sheets" },
       { name: "Ground beef", amount: "1 pound" },
     ],
     steps: [
       "Preheat oven to 375°F (190°C).",
       "Cook the lasagna noodles according to package instructions.",
     ]
   }
   ```

## Run the agent server

Learn how to interact with your agent through Mastra's API.

1. You can run your agent as a service using the `mastra dev` command:

   ```bash
   mastra dev
   ```

   This will start a server exposing endpoints to interact with your registered agents. Within [Studio](https://mastra.ai/docs/studio/overview) you can test your agent through a UI.

2. By default, `mastra dev` runs on `http://localhost:4111`. Your Chef Assistant agent will be available at:

   ```text
   POST http://localhost:4111/api/agents/chefAgent/generate
   ```

3. You can interact with the agent using `curl` from the command line:

   ```bash
   curl -X POST http://localhost:4111/api/agents/chefAgent/generate \
     -H "Content-Type: application/json" \
     -d '{
       "messages": [
         {
           "role": "user",
           "content": "I have eggs, flour, and milk. What can I make?"
         }
       ]
     }'
   ```

   **Sample Response:**

   ```json
   {
     "text": "You can make delicious pancakes! Here's a simple recipe..."
   }
   ```