chrono-mcp

The MCP server for time math at scale. Batch-crunch up to 100,000 timestamps in a single tool call, speak the industry's temporal interchange standards (RFC 9557 IXDTF, RFC 5545 RRULE, ISO 8601 repeating intervals), and give your agent a passive sense of passing time on every response. Powered by Luxon, DST-correct by construction, and every limit is benchmark-backed.

Quick Start

npx @jmoak/chrono-mcp

Run as local HTTP server

npm install
npm run build
npm run start:http
# Server listens on http://localhost:8000/mcp (health check at /health)

MCP Client Configuration

Configure your MCP client to launch chrono-mcp via npx. Below are client-specific examples.

Claude Code

Ask Claude! Here's the configuration:

{
  "mcpServers": {
    "chrono-mcp": {
      "command": "npx",
      "args": ["-y", "@jmoak/chrono-mcp@latest"]
    }
  }
}

Cursor

Reference: Cursor MCP docs

{
  "mcpServers": {
    "chrono-mcp": {
      "command": "npx",
      "args": ["-y", "@jmoak/chrono-mcp@latest"]
    },
    "chrono-mcp-http": {
      "type": "http",
      "url": "http://localhost:8000/mcp"
    }
  }
}

Why chrono-mcp

LLMs are famously bad at time: they miscount weekdays, lose track of elapsed time between turns, and fall apart on DST math. chrono-mcp fixes all three — and does it at bulk scale, in the formats the rest of the industry already speaks.

• Bulk by design - 10,000 calculations per request for per-item operations; 100,000 timestamps for stats, which returns pure aggregates. Every cap is proven by a benchmark you can run yourself (npm run bench) — per-item ops finish in under 100ms at the cap, 100k-item stats in ~460ms
• RFC 9557 (IXDTF) Interchange - All datetime inputs accept bracketed IANA zone annotations (2026-08-09T15:00:00-04:00[America/New_York]) with Temporal-compatible offset-consistency validation, plus an ixdtf output format — the serialization standard of the JS Temporal API
• Recurrence Expansion - expand turns RFC 5545 RRULEs (the format Google Calendar, Outlook, and Apple Calendar store) and ISO 8601 repeating intervals into concrete occurrences — DST-correct, window-bounded, with explicit truncation reporting
• Temporal Context Envelope - Every tool response carries a compact trailing line with the current time, weekday, elapsed time since the agent's previous call, session age, and tzdb version — passive time-awareness on every interaction
• Batch Error Isolation - One bad timestamp doesn't sink a 10,000-item batch: invalid entries are skipped and reported (invalid_count + samples), never silently dropped
• Token-Optimized Output - Dynamically shaped responses that maximize information density while minimizing token usage
• Global Timezone Support - All IANA timezone identifiers, wit

... View full README on GitHub