Exact U.S. federal holidays and business-day arithmetic for 1971-2100, so your assistant does not guess at observed dates. It knows the OPM rule (a Saturday holiday is observed Friday) and the Federal Reserve rule (banks stay open that Friday).
MCP endpoint, Streamable HTTP, no token needed:
https://us-federal-holidays-business-days-mcp.lipmichal.workers.dev/mcp
Claude.ai custom connector or ChatGPT developer mode: paste the URL above.
Claude Code: claude mcp add --transport http us-federal-holidays https://us-federal-holidays-business-days-mcp.lipmichal.workers.dev/mcp
Local stdio: npx -y github:theluckystrike/us-federal-holidays-business-days-mcp
| Tool | What it does |
|---|---|
| list_federal_holidays | All holidays for a year with legal, OPM observed and Federal Reserve dates |
| is_business_day | Business day check on the federal or Fed banking calendar |
| add_business_days | Add or subtract N business days |
| count_business_days | Business days between two dates |
| invoice_due_date | Due date from net terms, rolled past weekends and holidays |
Sources: OPM federal holidays, Federal Reserve K.8, 5 U.S.C. 6103. Code: GitHub.
Part of the Zovo MCP collection: mcp.zovo.one. The invoice and dunning servers in that bundle use these due dates.