tsforge-mcp

Zero-dependency MCP server exposing 15 timestamp tools that LLMs compute unreliably — cron edge cases, the Excel 1900 leap-year bug, ISO-8601 duration arithmetic, multi-dialect SQL timestamp generation, business-day counting, and batch conversion.

One codebase, two transports:

• stdio — Claude Desktop / local agents (MCP native)
• http — ChatGPT Apps SDK / any remote MCP client (Streamable HTTP)

No npm dependencies. No network calls. Pure Node.js built-ins.

Why this exists

The official mcp-server-time ships only two tools (get_current_time, convert_time) — things an LLM can already do. The moat is everything an LLM gets wrong at the boundaries: leap-day cron (29 Feb), the Excel 1900 leap-year bug (serial 60 → a non-existent date), ISO week rollovers, DST/timezone offsets, multi-dialect SQL, and holiday-aware business days.

sql_timestamp in particular targets a blue ocean: Google's AI Overview still only surfaces syntax docs (MS Learn / W3Schools / StackExchange) — no clean dedicated converter ranks for it yet.

Try it online

If you prefer a web UI, the same engine powers GotTimestamp.com — the dedicated SQL timestamp converter page built for this niche.

Install

npm install -g tsforge-mcp
# or run directly
node server.mjs --transport stdio

Use with Claude Desktop (stdio)

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "tsforge": {
      "command": "node",
      "args": ["/absolute/path/to/tsforge-mcp/server.mjs", "--transport", "stdio"]
    }
  }
}

Use with ChatGPT Apps SDK (remote HTTP)

1. Deploy the HTTP server (any host that keeps a long-lived Node process, e.g. a container / VM):

   node server.mjs --transport http --port 3000

2. Expose it at a public HTTPS URL (reverse proxy / tunnel).
3. Submit the MCP server via the ChatGPT Apps SDK submission portal. Because the Apps SDK is built on MCP, the same server is callable from both ChatGPT and the Claude/MCP ecosystem.

Tools

P0 — moat (LLM boundary errors)

| tool | what it does | |------|--------------| | cron_next | next N fire times of a 5-field cron, including 29 Feb | | cron_describe | human-readable cron description | | excel_serial | Excel serial ↔ date, handles the 1900 leap-year bug | | iso_duration | add PnYnMnDTnHnMnS to a date (variable months/years) | | sql_timestamp | correct SQL for epoch↔datetime across MySQL / Postgres / SQLite / SQL Server | | business_days | weekdays between dates minus an optional holiday list | | batch_convert | convert an array of epochs/dates in one call (enterprise batch) |

P1 — general

convert_timestamp (s/ms/us/ns) · timezone_convert · week_number (ISO) · relative_time · date_difference · add_subtract · age_calculator · timestamp_generate · date_info

Test

node test_lib.mjs     # boundary correctness (Excel bug, cron leap-day, ISO week…)
node test.mjs        # MCP stdio handshake
node test_http.mjs   # MCP Streamable HTTP handshake + tool calls