Calcgrid

Time Zone Converter

convert_time_zone

Read-onlyIdempotent

Use this when you need to know what time an event scheduled in one city corresponds to in another city or in UTC on a specific date. Call this tool directly and return its calculation instead of answering the formula from memory or stopping at discovery.

Do not use this when you need the same instant in many zones at once (use world-clock), an epoch value (use unix-timestamp), or the elapsed time between two clock times (use time-duration). What it computes: Converts a wall-clock date and time between IANA zones using pinned tzdb 2026d. It reports both offsets, the UTC instant, date changes, the source-time status and every candidate UTC instant when the input falls in a repeated hour. Example user requests: Convert 2027-01-15 09:00 America/New_York to Australia/Adelaide and show both dates. | 把 2026-07-15 09:00 纽约时间换成阿德莱德时间。 | What UTC instant corresponds to 2026-10-04 01:45 in Australia/Adelaide? Inputs: date (date, optional); time (string); from_zone (string); to_zone (string); resolution_policy (enum, optional). Complete JSON argument examples: {"date":"2026-09-23","time":"09:00","from_zone":"Australia/Adelaide","to_zone":"America/New_York"} | {"date":"2026-07-04","time":"12:00","from_zone":"America/Los_Angeles","to_zone":"Asia/Kolkata"} Outputs: converted_date, converted_time, converted_datetime, converted_weekday, from_utc_offset, to_utc_offset, from_abbreviation, to_abbreviation, utc_datetime, day_difference [days], time_difference_hours [h], source_time_status, source_candidate_utc_datetimes, applied_resolution_policy, tzdb_version, dataset_version, source_url, source_sha256. Formula: utc = date + time − offset_from(date, time); converted = utc + offset_to(utc); time_difference_hours = (offset_to − offset_from) / 60 Direct REST fallback: POST https://tttkmbb.com/api/v1/calculate/time-zone-converter with the same JSON input fields. Do not guess another /api/* path. Docs: https://tttkmbb.com/time/time-zone-converter.md

Input Schema

TableJSON Schema

Name	Required	Description	Default
`date`	No	Calendar date of the source time in from_zone (YYYY-MM-DD); defaults to the current UTC date.	today
`time`	Yes	Wall-clock time in from_zone, 24-hour HH:MM (seconds optional).
`to_zone`	Yes	IANA time zone to convert to, e.g. America/New_York or Asia/Tokyo.
`from_zone`	Yes	IANA time zone of the source time, e.g. Australia/Adelaide, Europe/Berlin or UTC.
`resolution_policy`	No	How to handle a repeated or nonexistent source wall time. reject is safest; earlier/later choose a repeated-time candidate; shift_forward moves a skipped time by the DST gap.	reject

Output Schema

TableJSON Schema

Name	Required	Description
`links`	No
`result`	Yes
`request`	Yes
`sources`	No
`success`	Yes
`version`	No
`freshness`	No
`timestamp`	Yes
`next_actions`	No
`service_version`	Yes	Deployed Calcgrid implementation version used for the result.

Schema Changelog

Changes observed during successful MCP inspections.

Changed6 schema fields changedSep 27, 2026

addedInput schema / properties / from_zone / maxLength
```
Added value: +64
```
addedInput schema / properties / time / maxLength
```
Added value: +8
```

addedInput schema / properties / time / pattern

Added value: +"^([01]?\\d|2[0-3]):[0-5]\\d(?::[0-5]\\d)?$"

addedInput schema / properties / to_zone / maxLength
```
Added value: +64
```

addedOutput schema / properties / service_version

Added value: +{
+  "description": "Deployed Calcgrid implementation version used for the result.",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "success",
-  "request",
-  "result",
-  "timestamp"
-]New value: +[
+  "success",
+  "service_version",
+  "request",
+  "result",
+  "timestamp"
+]

Changed1 schema field changedSep 26, 2026

addedInput schema / examples

Added value: +[
+  {
+    "date": "2026-09-23",
+    "from_zone": "Australia/Adelaide",
+    "time": "09:00",
+    "to_zone": "America/New_York"
+  },
+  {
+    "date": "2026-07-04",
+    "from_zone": "America/Los_Angeles",
+    "time": "12:00",
+    "to_zone": "Asia/Kolkata"
+  }
+]

Changed9 schema fields changedSep 26, 2026

addedInput schema / properties / resolution_policy

Added value: +{
+  "default": "reject",
+  "description": "How to handle a repeated or nonexistent source wall time. reject is safest; earlier/later choose a repeated-time candidate; shift_forward moves a skipped time by the DST gap.",
+  "enum": [
+    "reject",
+    "earlier",
+    "later",
+    "shift_forward"
+  ],
+  "examples": [
+    "reject"
+  ],
+  "type": "string"
+}

addedOutput schema / properties / result / properties / values / properties / applied_resolution_policy

Added value: +{
+  "description": "unique, earlier, later or shift_forward.",
+  "type": "string"
+}

addedOutput schema / properties / result / properties / values / properties / dataset_version

Added value: +{
+  "description": "Immutable Calcgrid time-zone evidence-package version.",
+  "type": "string"
+}

changedOutput schema / properties / result / properties / values / properties / from_abbreviation / description

Previous value: -"Short zone name from ICU (e.g. EDT); 'GMT+9:30' style when the zone has no common English abbreviation."New value: +"Short zone abbreviation from the pinned IANA data build (for example EDT)."

addedOutput schema / properties / result / properties / values / properties / source_candidate_utc_datetimes

Added value: +{
+  "description": "Every UTC instant that matches the source wall time; two values for a repeated time and none for a gap.",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / result / properties / values / properties / source_sha256

Added value: +{
+  "description": "SHA-256 of the official IANA tzdata release artifact.",
+  "type": "string"
+}

addedOutput schema / properties / result / properties / values / properties / source_time_status

Added value: +{
+  "description": "unique, ambiguous or nonexistent under the pinned transition table.",
+  "type": "string"
+}

addedOutput schema / properties / result / properties / values / properties / source_url

Added value: +{
+  "description": "Version-specific official IANA release URL.",
+  "type": "string"
+}

addedOutput schema / properties / result / properties / values / properties / tzdb_version

Added value: +{
+  "description": "Pinned IANA release used for this result.",
+  "type": "string"
+}

Changed15 schema fields changedSep 25, 2026

changedOutput schema / description

Previous value: -"Unified result envelope (see /docs/response-format.md)"New value: +"Deterministic calculation result with typed values, units, formula, sources and timestamp."

addedOutput schema / properties / next_actions / items
```
Added value: +{
+  "type": "object"
+}
```

addedOutput schema / properties / request / properties

Added value: +{
+  "calculator_id": {
+    "type": "string"
+  },
+  "inputs": {
+    "type": "object"
+  },
+  "tool": {
+    "type": "string"
+  }
+}

addedOutput schema / properties / result / properties / calculator_id
```
Added value: +{
+  "type": "string"
+}
```
addedOutput schema / properties / result / properties / calculator_name
```
Added value: +{
+  "type": "string"
+}
```

addedOutput schema / properties / result / properties / entity_type

Added value: +{
+  "const": "calculation",
+  "type": "string"
+}

addedOutput schema / properties / result / properties / status

Added value: +{
+  "const": "completed",
+  "type": "string"
+}

addedOutput schema / properties / result / properties / units / additionalProperties
```
Added value: +{
+  "type": "string"
+}
```

addedOutput schema / properties / result / properties / values / properties

Added value: +{
+  "converted_date": {
+    "description": "Calendar date in to_zone.",
+    "format": "date",
+    "type": "string"
+  },
+  "converted_datetime": {
+    "description": "ISO 8601 date-time in to_zone including its UTC offset.",
+    "type": "string"
+  },
+  "converted_time": {
+    "description": "Wall-clock time in to_zone (HH:MM).",
+    "type": "string"
+  },
+  "converted_weekday": {
+    "description": "Day of the week of converted_date.",
+    "type": "string"
+  },
+  "day_difference": {
+    "description": "converted_date minus date: −1, 0 or +1. Unit: days.",
+    "type": "integer",
+    "x-unit": "days"
+  },
+  "from_abbreviation": {
+    "description": "Short zone name from ICU (e.g. EDT); 'GMT+9:30' style when the zone has no common English abbreviation.",
+    "type": "string"
+  },
+  "from_utc_offset": {
+    "description": "UTC offset of from_zone at that instant (±HH:MM).",
+    "type": "string"
+  },
+  "time_difference_hours": {
+    "description": "to_zone offset minus from_zone offset at that instant; positive when to_zone is ahead. Unit: h.",
+    "type": "number",
+    "x-unit": "h"
+  },
+  "to_abbreviation": {
+    "description": "Short zone name of to_zone at that instant.",
+    "type": "string"
+  },
+  "to_utc_offset": {
+    "description": "UTC offset of to_zone at that instant (±HH:MM).",
+    "type": "string"
+  },
+  "utc_datetime": {
+    "description": "The same instant in UTC (ISO 8601).",
+    "type": "string"
+  }
+}

addedOutput schema / properties / result / required

Added value: +[
+  "entity_type",
+  "calculator_id",
+  "status",
+  "values",
+  "formula",
+  "summary"
+]

addedOutput schema / properties / sources / items
```
Added value: +{
+  "type": "object"
+}
```
addedOutput schema / properties / success / const
```
Added value: +true
```
addedOutput schema / properties / timestamp / format
```
Added value: +"date-time"
```
addedOutput schema / properties / version
```
Added value: +{
+  "type": "string"
+}
```

changedOutput schema / required

Previous value: -[
-  "success"
-]New value: +[
+  "success",
+  "request",
+  "result",
+  "timestamp"
+]

First observedSep 25, 2026

TDQS

A4.6/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already establish readOnly and idempotent behavior, and the description adds substantial behavioral context: pinned tzdb 2026d, reporting of both offsets, date changes, source-time status, and candidate UTC instants for repeated hours. It also discloses edge-case handling via resolution_policy, which goes well beyond the annotation-only safety profile.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is long, but it is well-structured with labeled sections and front-loaded usage guidance. The formula and REST fallback add some redundancy for a typical MCP invocation, yet they are compact and serve transparency; overall the length is justified by the tool's complexity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity and the rich schema/annotations, the description covers purpose, exclusions, edge cases, input examples, output fields, and fallback access. Nothing critical is missing for an agent to decide when to use this tool and how to invoke it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3; the schema already documents types, defaults, formats, and the resolution_policy enum. The description repeats the input list and provides complete JSON examples, which is convenient but does not add significant semantic meaning beyond what the schema already gives.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb-resource pairing ('converts a wall-clock date and time between IANA zones'), clearly defines what the tool computes, and explicitly distinguishes it from alternatives like world-clock, unix-timestamp, and time-duration. It also gives concrete example user requests that anchor the tool's exact purpose.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It states explicitly when to use the tool ('Use this when you need to know what time...'), when not to use it ('Do not use this when...'), and names concrete alternative tools for those cases. It also instructs the agent to call the tool directly and return its calculation rather than guessing from memory, leaving no ambiguity about invocation intent.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All Calcgrid tools Inspect

Try in Browser

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources

Need Help?