Nuntly MCP Server

@nuntly/sdk-mcp

MCP server for Nuntly, the developer-first email platform. Exposes tools for sending emails, managing domains, webhooks, inboxes, and more.

Documentation | SDK Reference | Get your API key

Table of contents

• Requirements
• Setup
• Environment variables
• Programmatic usage
• Tools
• FAQ
• Semantic versioning
• Previous versions
• Contributing
• License

Requirements

• Node.js 20 or later (or Bun)
• A Nuntly API key from https://nuntly.com/auth/sign-up
• An MCP-aware client: Claude Desktop, Claude Code, Cursor, Continue, or any custom integration based on the Model Context Protocol

Setup

Claude Desktop

Add to your Claude Desktop config:

OS	Path
macOS	~/Library/Application Support/Claude/claude_desktop_config.json
Windows	%APPDATA%\Claude\claude_desktop_config.json
Linux	~/.config/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "nuntly": {
      "command": "npx",
      "args": ["@nuntly/sdk-mcp"],
      "env": {
        "NUNTLY_API_KEY": "your-api-key"
      }
    }
  }
}

Claude Code

Use the built-in claude mcp add command:

claude mcp add nuntly -- npx @nuntly/sdk-mcp

Then export NUNTLY_API_KEY in your shell, or paste this shape into .mcp.json manually:

{
  "mcpServers": {
    "nuntly": {
      "command": "npx",
      "args": ["@nuntly/sdk-mcp"],
      "env": {
        "NUNTLY_API_KEY": "your-api-key"
      }
    }
  }
}

Cursor

Add to your Cursor MCP settings:

{
  "mcpServers": {
    "nuntly": {
      "command": "npx",
      "args": ["@nuntly/sdk-mcp"],
      "env": {
        "NUNTLY_API_KEY": "your-api-key"
      }
    }
  }
}

Environment variables

Variable	Required	Description
NUNTLY_API_KEY	Yes	Your Nuntly API key
NUNTLY_BASE_URL	No	Custom API base URL (default: https://api.nuntly.com)

Programmatic usage

Embed the server

createMcpServer returns a fully-configured McpServer (all tools registered); connect it to any transport yourself.

import { createMcpServer } from '@nuntly/sdk-mcp/ai';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';

const server = createMcpServer({ apiKey: process.env.NUNTLY_API_KEY });
await server.connect(new StdioServerTransport());

Custom integration

import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { Nuntly } from '@nuntly/sdk';
import { registerTools } from '@nuntly/sdk-mcp';

const server = new McpServer({ name: 'my-server', version: '1.0.0' });
const nuntly = new Nuntly({ apiKey: process.env.NUNTLY_API_KEY });
registerTools(server, nuntly);

Tools

Tools available:

Agents: retrieve-agent-memory, upsert-agent-memory

API Keys: create-api-key, delete-api-key, list-api-keys, retrieve-api-key, update-api-key

Domains: create-domain, delete-domain, list-domains, retrieve-domain, update-domain

Emails: cancel-email, list-emails, retrieve-bulk-emails, retrieve-email, retrieve-email-content, retrieve-email-events, retrieve-email-stats, send-bulk-emails, send-email

Inboxes: create-inbox, delete-inbox, list-inboxes, retrieve-inbox, send-inbox-message, update-inbox

Messages: forward-message, list-message-attachments, list-messages, reply-to-message, retrieve-message, retrieve-message-attachment, retrieve-message-content, update-message

Namespaces: create-namespace, delete-namespace, list-namespace-inboxes, list-namespaces, retrieve-namespace, update-namespace

Organizations: list-organizations, retrieve-organization, retrieve-organization-usage

Threads: list-inbox-threads, list-thread-messages, retrieve-thread, update-thread

Webhooks: create-webhook, delete-webhook, list-webhooks, retrieve-webhook, update-webhook

Webhooks Events: list-webhook-event-deliveries, list-webhooks-events, replay-webhook-event

FAQ

Does this require Node.js or Bun? Either. The published package runs on Node.js 20+ via npx @nuntly/sdk-mcp and on Bun via bunx @nuntly/sdk-mcp. Most MCP clients spawn npx directly.

Do I need an LLM provider account? No. The MCP server only talks to the Nuntly API. The LLM client (Claude Desktop, Cursor, etc.) handles its own provider authentication.

How do I report a bug or request a tool? Open an issue at github.com/nuntly/nuntly-mcp/issues.

Semantic versioning

This package follows Semantic Versioning 2.0. The published version tracks the underlying Nuntly SDK version closely. New tools and tool argument additions are minor bumps; tool removals or argument breaking changes are major bumps.

Previous versions

Versions 0.x remain installable from npm via npm install @nuntly/sdk-mcp@0 for backwards compatibility.

Contributing

Issues, bug reports, and feature requests are welcome at github.com/nuntly/nuntly-mcp/issues.

Troubleshooting

Server does not appear in the Claude Desktop tools list Validate the JSON syntax of claude_desktop_config.json (a trailing comma silently breaks the whole file), fully quit and restart Claude Desktop, and confirm the command path resolves on your $PATH (try running it from a terminal first).

NUNTLY_API_KEY missing at startup Grab a key from nuntly.com and paste it under env in your MCP client config. The server reads the variable from the spawned process environment, not from your shell.

Tool returns isError: true The structured content block contains an error object with status, code, and requestId. Use the requestId when contacting support. A 401 means the API key is missing, revoked, or scoped to a different organization.

command not found: npx Install Node.js 20 or later from nodejs.org. npx ships with Node and is the spawn target used by every MCP client in the examples above.

License

MIT. See LICENSE.