# Holiday Calendar MCP server

U.S. federal holidays with observed dates and business-day math. Example from an open-source kit.

## At a glance

Holiday Calendar is an MCP server in the Productivity category. It is hosted remotely and connects over HTTP, and declares no required credentials. It exposes 5 tools, including list_federal_holidays, next_federal_holidays and check_business_day. It scores B (73/100) on the MCP Skills Hub health score as of Oct 28, 2026.

## Install

### How to install Holiday Calendar in Claude Code

1. Add the server

```bash
claude mcp add --transport http holiday-calendar https://starter.modernmustardseed.com/holidays
```

2. Verify it's connected

```bash
claude mcp list
```

3. Sharing it with your team?

   Add `--scope project` to write it to .mcp.json in the repository root, which you can commit (with the secrets left as environment variables).

4. Use it in a session

   Ask Claude to use the tools this server exposes (e.g. list_federal_holidays, next_federal_holidays, check_business_day). It discovers them automatically.

### How to install Holiday Calendar in Claude Desktop

1. Open your MCP config

   macOS: ~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Add this server

```json
{
  "mcpServers": {
    "holiday-calendar": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://starter.modernmustardseed.com/holidays"
      ]
    }
  }
}
```

3. Why the wrapper?

   This is a remote (HTTP) server and Claude Desktop only launches local processes, so mcp-remote proxies the connection. It will open a browser window if the server needs OAuth.

4. Restart Claude Desktop

   The tools appear under the 🔌 menu once the app reloads.

### How to install Holiday Calendar in Cursor

1. Create / edit .cursor/mcp.json in your project

```json
{
  "mcpServers": {
    "holiday-calendar": {
      "url": "https://starter.modernmustardseed.com/holidays"
    }
  }
}
```

2. Enable it

   Cursor Settings → MCP → toggle the server on. Tools become available to the Composer/Agent.

### How to install Holiday Calendar in Codex CLI

1. Add to ~/.codex/config.toml

```toml
[mcp_servers.holiday-calendar]
command = "npx"
args = ["-y", "mcp-remote", "https://starter.modernmustardseed.com/holidays"]
```

2. Why the wrapper?

   Codex runs MCP servers as local processes, so mcp-remote bridges this HTTP endpoint to stdio.

3. Run Codex

   Codex loads MCP servers from config.toml on startup and exposes their tools to the agent.

### How to install Holiday Calendar in Windsurf

1. Edit ~/.codeium/windsurf/mcp_config.json

```json
{
  "mcpServers": {
    "holiday-calendar": {
      "serverUrl": "https://starter.modernmustardseed.com/holidays"
    }
  }
}
```

2. Reload

   Windsurf → Cascade → refresh MCP servers. Cascade can now call the tools.

### How to install Holiday Calendar in Cline

1. Open Cline → MCP Servers → Configure

   Adds to cline_mcp_settings.json.

2. Add the server

```json
{
  "mcpServers": {
    "holiday-calendar": {
      "type": "streamableHttp",
      "url": "https://starter.modernmustardseed.com/holidays"
    }
  }
}
```

### How to install Holiday Calendar in VS Code

1. Create .vscode/mcp.json

```json
{
  "servers": {
    "holiday-calendar": {
      "type": "http",
      "url": "https://starter.modernmustardseed.com/holidays"
    }
  }
}
```

2. Start it

   VS Code shows a ▶ Start action above the server entry. Agent mode (Copilot Chat) can then use the tools.

## Tools

- `list_federal_holidays` — List the eleven U.S. federal holidays for one calendar year (2021 through 2100): each holiday's name, its actual date and weekday, the date it is observed when it falls on a weekend (Saturday moves to the Friday before, Sunday to the Monday after), and the rule that sets it, from 5 U.S.C. 6103. Use it to answer which days federal offices close in a year.
- `next_federal_holidays` — Find the next one to eleven U.S. federal holidays observed on or after a date, with each one's observed date and how many calendar days away it is. Without from_date it starts from today's date in America/New_York and says which date it used.
- `check_business_day` — Check whether a date is a U.S. business day (a weekday that is not an observed federal holiday). Returns the weekday, the holiday observed that day if any, and the business days just before and just after it.
- `add_business_days` — Move a number of U.S. business days forward or backward from a date, skipping weekends and observed federal holidays, for due dates, delivery windows and notice periods. The start date is not counted: 1 business day after a Friday is the next Monday, or Tuesday when that Monday is a holiday. Returns the resulting date and every holiday it skipped. Up to 1,000 business days either way.
- `count_business_days` — Count the U.S. business days between two dates, both dates included, leaving out weekends and observed federal holidays. Returns the business day count, the weekend days, and each holiday that fell in the span. Spans up to 3,660 calendar days.

Source repository: https://github.com/ModernMustardSeed/small-business-mcp-starter

---

Source: https://mcp-skills-hub.vercel.app/mcps/com-modernmustardseed-holiday-calendar · MCP Skills Hub · data as of 2026-10-28T12:31:05Z