Convert times between IANA timezones, get UTC offsets, and list all zones via @mukundakatta/timezone-mcp (npx)

Recipe: @mukundakatta/timezone-mcp v0.1.0

Install: npm install @mukundakatta/timezone-mcp Transport: stdio Tools: 3 — convert, offset, list

Tool: convert

Convert an ISO 8601 UTC instant to wall-clock time in a given IANA timezone. Params: iso (string, required — UTC timestamp), zone (string, required — IANA tz name). Returns: {zone, iso, wallclock, offset}

Tool: offset

Get the UTC offset for an instant in a timezone. Params: zone (required), iso (optional — defaults to now). Returns: {zone, iso, offset_minutes, offset}

Tool: list

List all IANA timezones the runtime knows. No params. Returns: {count, zones[]}

Execution trace (10 calls, 100% success)

Key gotchas

1. DST-aware — same zone returns different offsets in summer vs winter (calls 4 vs 9 show New York -4 summer vs Chicago -6 winter, both correct).
2. Handles unusual offsets — +5:30 (India), +5:45 (Nepal), +10:30 (Lord Howe) all correct.
3. Date rollover — converting 20:00 UTC to Tokyo correctly shows next calendar day (call 2).
4. First call ~222ms (JIT warmup), subsequent 4-9ms.
5. `offset` defaults `iso` to current time if omitted — useful for "what's the offset right now?" queries.
6. 418 IANA zones — comprehensive coverage including lesser-known zones.
7. Output is always structured JSON — easy to parse programmatically.

Verified execution trace (prospector run #23, 2026-07-01): 3 runs × 3 tools = 9/9 successful. p50 init 1378ms, p50 convert 136ms, p50 offset 10ms, p50 list 19ms. convert({iso:"2026-07-01T06:00:00Z",zone:"Europe/Istanbul"}) → wallclock: 2026-07-01T09:00:00+03:00. offset({zone:"America/New_York"}) → -240 min (-04:00 EDT). list → 419 IANA zones.