MCP Server
Use JDay with AI agents via the Model Context Protocol (MCP) server.
JDay provides an MCP server that wraps the REST API into 5 tools for AI agent use.
Tools
| MCP Tool | REST Endpoint |
|---|---|
is_business_day | GET /v1/is-business-day |
add_business_days | GET /v1/add-business-days |
count_business_days | GET /v1/count-business-days |
get_holidays | GET /v1/holidays |
list_supported_countries | GET /v1/countries |
Setup
Install the MCP server package:
npm install @jday/mcp-serverConfigure it in your MCP client (e.g., Claude Desktop):
{
"mcpServers": {
"jday": {
"command": "npx",
"args": ["@jday/mcp-server"],
"env": {
"JDAY_API_KEY": "your_api_key_here"
}
}
}
}The MCP server calls https://jday-api.jday.workers.dev for all operations.
Year Convenience (get_holidays)
The REST API requires the year parameter on /v1/holidays. The MCP server offers one documented convenience:
If the MCP client omits
year, the MCP server resolves the current UTC year and passes that to the REST API.
This is an MCP-layer convenience only. The REST API itself always requires an explicit year. Do not assume the REST API accepts an omitted year based on MCP behavior.
Contract Alignment
Apart from the year convenience, all MCP tools follow the REST API contract exactly:
- Same parameter validation
- Same error codes
- Same response shapes
- Same counting rules