@tooly/resend

Resend API tools for OpenAI, Anthropic, and AI SDK. Convert Resend's email API into AI-compatible tools for sending, retrieving, updating, and canceling emails.

Installation

npm install @tooly/resend
# or
pnpm add @tooly/resend
# or
yarn add @tooly/resend

Features

• sendEmail: Send a single email
• sendBatchEmails: Send up to 100 batch emails at once
• retrieveEmail: Retrieve email details by ID
• updateEmail: Update a scheduled email
• cancelEmail: Cancel a scheduled email

Quick Start

Basic Usage

import { ResendTools } from '@tooly/resend'

const resendTools = new ResendTools('your-resend-api-key')

// Get all available tools
const tools = resendTools.getTools()

// Execute a function directly
const result = await resendTools.executeFunction('sendEmail', {
  from: '[email protected]',
  to: ['[email protected]'],
  subject: 'Hello from Resend!',
  html: '<p>This is a test email.</p>',
})

Usage with OpenAI

import OpenAI from 'openai'
import { createOpenAIFunctions } from '@tooly/resend'

const openai = new OpenAI({
  apiKey: 'your-openai-api-key',
})

const { tools, executeFunction } = createOpenAIFunctions('your-resend-api-key')

const completion = await openai.chat.completions.create({
  model: 'gpt-4.1-nano',
  messages: [
    {
      role: 'user',
      content: 'Send a welcome email to [email protected] with the subject "Welcome to our platform!"',
    },
  ],
  tools: tools.map((tool) => ({
    type: 'function',
    function: tool,
  })),
})

// Handle function calls
const message = completion.choices[0].message
if (message.tool_calls) {
  for (const toolCall of message.tool_calls) {
    if (toolCall.type === 'function') {
      const result = await executeFunction(toolCall.function.name, JSON.parse(toolCall.function.arguments))
      console.log('Email sent:', result)
    }
  }
}

Usage with Anthropic

import Anthropic from '@anthropic-ai/sdk'
import { createAnthropicTools } from '@tooly/resend'

const anthropic = new Anthropic({
  apiKey: 'your-anthropic-api-key',
})

const { tools, executeFunction } = createAnthropicTools('your-resend-api-key')

const message = await anthropic.messages.create({
  model: 'claude-sonnet-4-20250514',
  max_tokens: 1024,
  messages: [
    {
      role: 'user',
      content: 'Send a welcome email to [email protected]',
    },
  ],
  tools: tools,
})

// Handle function calls
if (message.content.some((content) => content.type === 'tool_use')) {
  for (const content of message.content) {
    if (content.type === 'tool_use') {
      const result = await executeFunction(content.name, content.input)
      console.log('Email sent:', result)
    }
  }
}

Usage with AI SDK

import { generateText } from 'ai'
import { openai } from '@ai-sdk/openai'
import { createAITools } from '@tooly/resend'

const tools = createAITools('your-resend-api-key')

const { text } = await generateText({
  model: openai('gpt-4.1-nano'),
  prompt: 'Send a welcome email to [email protected] with subject "Welcome!"',
  tools: tools,
})

console.log(text)

API Reference

ResendTools

Main class for managing Resend tools.

const resendTools = new ResendTools(apiKey: string);

Methods

• getTools(): Returns all available tool definitions
• executeFunction(name: string, parameters: any): Execute a tool function by name
• getHandlers(): Get direct access to handler methods

Available Tools

sendEmail

Send a single email using Resend.

Parameters:

• from (string, required): Sender email address
• to (string[], required): Recipient email addresses (max 50)
• subject (string, required): Email subject
• html (string, optional): HTML version of the message
• text (string, optional): Plain text version of the message
• bcc (string[], optional): BCC recipients
• cc (string[], optional): CC recipients
• reply_to (string[], optional): Reply-to addresses
• scheduled_at (string, optional): Schedule email for later
• headers (object, optional): Custom headers
• attachments (array, optional): File attachments
• tags (array, optional): Custom tags for tracking

Example:

await executeFunction('sendEmail', {
  from: '[email protected]',
  to: ['[email protected]'],
  subject: 'Hello!',
  html: '<p>Hello world!</p>',
  text: 'Hello world!',
})

sendBatchEmails

Send up to 100 batch emails at once.

Parameters:

• emails (array, required): Array of email objects (max 100)

Example:

await executeFunction('sendBatchEmails', {
  emails: [
    {
      from: '[email protected]',
      to: ['[email protected]'],
      subject: 'Hello User 1!',
      html: '<p>Hello User 1!</p>',
    },
    {
      from: '[email protected]',
      to: ['[email protected]'],
      subject: 'Hello User 2!',
      html: '<p>Hello User 2!</p>',
    },
  ],
})

retrieveEmail

Retrieve details of a single email by ID.

Parameters:

• id (string, required): The email ID to retrieve

Example:

await executeFunction('retrieveEmail', {
  id: '49a3999c-0ce1-4ea6-ab68-afcd6dc2e794',
})

updateEmail

Update a scheduled email.

Parameters:

• id (string, required): The email ID to update
• scheduled_at (string, optional): New scheduled time

Example:

await executeFunction('updateEmail', {
  id: '49a3999c-0ce1-4ea6-ab68-afcd6dc2e794',
  scheduled_at: 'in 2 hours',
})

cancelEmail

Cancel a scheduled email.

Parameters:

• id (string, required): The email ID to cancel

Example:

await executeFunction('cancelEmail', {
  id: '49a3999c-0ce1-4ea6-ab68-afcd6dc2e794',
})

Environment Variables

You can set your Resend API key as an environment variable:

RESEND_API_KEY=your-resend-api-key

Then use it in your code:

const resendTools = new ResendTools(process.env.RESEND_API_KEY!)

Error Handling

All functions include proper error handling and will throw descriptive errors:

try {
  const result = await executeFunction('sendEmail', {
    from: 'invalid-email',
    to: ['[email protected]'],
    subject: 'Test',
  })
} catch (error) {
  console.error('Failed to send email:', error.message)
}

TypeScript Support

This package includes full TypeScript support with proper type definitions:

import type { SendEmailParams, EmailResponse, EmailDetails } from '@tooly/resend'

Requirements

• Node.js 18+
• A Resend API key (get one at resend.com)
• A verified domain in Resend (for sending from your own domain)

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.