How to Use the Holiday API MCP in LangChain

Q: What's the best way to handle multiple countries with Holiday API and LangChain?

Use listsupportedcountries to get all valid country codes. Then you can use a map operation in your chain to run getholidays for each country in parallel. This is how you build a dashboard for global operations.

Build logistics and payroll chains that actually understand global holidays. This is the Holiday API for LangChain.

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Connect Holiday API MCP to LangChain

Create your Vinkius account to connect Holiday API to LangChain and route execution through our secure gateway. The platform manages server hosting, runtime updates, and security layers. Configuration requires no manual server provisioning.

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Setup Holiday API with LangChain

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Chain Holiday Lookups into Date Calculations

Stop guessing at delivery dates. This MCP Server gives your LangChain agent tools to build real-world logistics timelines. Start by checking for blackout dates with `get_holidays`, then use `get_workdays_count` to calculate the exact number of business days available between two points in time. Don't just get a number — get a date. The output from one tool feeds directly into the next. Once you know the workday count, you can use `get_next_workday` to pinpoint the final delivery or payroll date. It's a simple, observable chain that respects local calendars.

Build Globally-Aware LangChain Agents

Your agent needs to know its own limits. Before you even try to calculate a date, use `list_supported_countries` to confirm the API covers the region you're targeting. This prevents your chain from failing unexpectedly on an unsupported country code. Then, use `list_supported_languages` to fetch holiday names in the local language. You can build chains that not only calculate dates correctly but also report their findings in a way that local teams can understand. No extra translation steps needed.

Calculate Project Timelines, Not Just Dates

This isn't just for shipping. Use the same tools to build project management agents. Your LangChain agent can take a start date and a required number of 'effort-days', then use `get_next_workday` to calculate a realistic completion date, automatically skipping weekends and public holidays. This makes resource planning straightforward. You feed the agent a country and a timespan, and it returns a work calendar. It's a practical way to connect your agent's reasoning to the real-world flow of time.

Setup guide

Set up Holiday API MCP in LangChain

Prerequisites

Python 3.10+ installed
langchain-mcp-adapters + langgraph packages
Active Vinkius subscription with a valid endpoint token

1

Install dependencies
Run pip install langchain-mcp-adapters langgraph langchain-openai. The MCP adapters package converts MCP tools into native LangChain BaseTool objects.
2

Connect via HTTP transport
Use MultiServerMCPClient with "transport": "http" pointing to your Vinkius endpoint. Replace [YOUR_TOKEN_HERE] with your token from cloud.vinkius.com.
3

Create a ReAct agent
Pass the discovered tools to create_react_agent() from LangGraph. The agent automatically routes Holiday API tool calls through the MCP protocol.
4

Run with any LLM
Swap ChatOpenAI for ChatAnthropic, ChatGoogleGenerativeAI, or any LangChain-compatible model. The MCP tools work identically across all providers.

agent.py

from langchain_mcp_adapters.client import MultiServerMCPClient
from langgraph.prebuilt import create_react_agent
from langchain_openai import ChatOpenAI

async with MultiServerMCPClient({
    "holiday-api-mcp": {
        "transport": "http",
        "url": "https://edge.vinkius.com/[YOUR_TOKEN_HERE]/mcp",
    }
}) as client:
    tools = client.get_tools()

    agent = create_react_agent(
        ChatOpenAI(model="gpt-4o"),
        tools,
    )
    result = await agent.ainvoke({
        "messages": "List recent Holiday API transactions"
    })
    print(result["messages"][-1].content)

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Independent Platform Disclaimer: Vinkius is an independent platform and is not affiliated with, endorsed by, sponsored by, verified by, or otherwise authorized by Holiday API. All third-party trademarks, logos, and brand names are the property of their respective owners. Their use on this website is strictly for informational purposes to identify service compatibility and interoperability.

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Common questions about Holiday API MCP in LangChain

You get the tools from the MCP client and pass them to your agent executor. The agent then selects the right tool, like `get_holidays`, based on the prompt. Each tool call is just another runnable component in your chain.

Yes. Every tool call made by your agent, including calls to this MCP Server, is automatically traced in LangSmith. You'll see the exact inputs, outputs, and latency for each holiday or workday calculation.

Use `list_supported_countries` to get all valid country codes. Then you can use a map operation in your chain to run `get_holidays` for each country in parallel. This is how you build a dashboard for global operations.

No, the MCP server itself is stateless. Caching is your agent's job. You can wrap the tool calls in a `RunnableWithCache` to store results for common queries, like this year's holidays for your main office.

It only processes the country codes, years, and dates you send. Vinkius runs each MCP Server in an ephemeral sandbox. Your agent's requests are isolated and the server instance is destroyed after it's done, so your query data isn't stored.

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