# Holiday Calendar

This MCP server handles U.S. federal holidays, observed dates, and business-day calculations. Use it when an agent needs a date based on working days.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI
- Author: ModernMustardSeed
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/ModernMustardSeed/small-business-mcp-starter
- Updated: 2026-10-12
- HTML: https://affpapa.org/en/nevibecode/mcp/holiday-calendar

## What it does

Holiday Calendar gives an AI client access to a U.S. federal holiday calendar. It accounts for observed holiday dates and can calculate business-day offsets, such as finding when an invoice becomes due.

The sample connector exposes five read-only tools over HTTP at `https://starter.modernmustardseed.com/holidays`. It can be connected to Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, and the other listed clients. A self-hosted setup following the kit’s deployment path relies on Node 22.6 or newer, `pnpm`, and a Vercel account.

## Requirements
- Remote server: `https://starter.modernmustardseed.com/holidays`

## Install

### Claude Code (native platform)

**Platform CLI: remote server**
```bash
claude mcp add --transport http holiday-calendar https://starter.modernmustardseed.com/holidays
```

### Codex

**Platform CLI: remote server**
```bash
codex mcp add holiday-calendar --url https://starter.modernmustardseed.com/holidays
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "holiday-calendar": {
            "url": "https://starter.modernmustardseed.com/holidays"
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "holiday-calendar": {
            "type": "http",
            "url": "https://starter.modernmustardseed.com/holidays"
        }
    }
}
```

### Gemini CLI

**Platform CLI: remote server**
```bash
gemini mcp add -t http holiday-calendar https://starter.modernmustardseed.com/holidays
```

## When to use it
- calculate a due date from a number of business days
- account for an observed U.S. federal holiday
- check whether a date is a business day
- find upcoming U.S. federal holidays

## Example prompts
- Calculate the due date for an invoice dated 2026-11-20 with a 10-business-day term.
- Check whether 2026-11-26 is a U.S. federal holiday.
- List upcoming U.S. federal holidays together with their observed dates.

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---
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