# ISO Week Number (remote · iso-week.gumballtools.com)

ISO 8601 week numbers: date to week, week to date, weeks-per-year.

- Trust score: 74/100 (medium)
- Change this week: +3
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-25

## Components

- remote · `iso-week.gumballtools.com`: 74/100 (this document), [markdown](https://verifymcp.io/servers/com-gumballtools-iso-week/api-mcp.md), [page](https://verifymcp.io/servers/com-gumballtools-iso-week/api-mcp)

## Channel facts

- Endpoint: `https://iso-week.gumballtools.com/api/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `0.1.0`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-09-25.

- **Endpoint Security**: 63/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - Authorisation not fully verified: no authorisation is required to call this server, and 1 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe.
  - HTTPS is enforced; there's no plaintext access path.
  - The HSTS (Strict-Transport-Security) header is present.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 68/100
  - AI-judged instruction clarity (excellent).
  - Context-footprint check failed: tool/resource definitions use about 549 tokens (~549/item across 1 items; 1 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 63/100
  - Stability observed for 19 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 1 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 1 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a current MCP spec version (2026-07-28).

## Install

### How do I install the ISO Week Number MCP server?

ISO Week Number is a hosted endpoint at https://iso-week.gumballtools.com/api/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add --transport http com-gumballtools-iso-week 'https://iso-week.gumballtools.com/api/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "com-gumballtools-iso-week": {
      "url": "https://iso-week.gumballtools.com/api/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "com-gumballtools-iso-week": {
      "type": "http",
      "url": "https://iso-week.gumballtools.com/api/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.com-gumballtools-iso-week]
url = "https://iso-week.gumballtools.com/api/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "com-gumballtools-iso-week": {
      "type": "remote",
      "url": "https://iso-week.gumballtools.com/api/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add com-gumballtools-iso-week --url 'https://iso-week.gumballtools.com/api/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  com-gumballtools-iso-week:
    url: "https://iso-week.gumballtools.com/api/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "com-gumballtools-iso-week": {
      "Transport": "http",
      "Url": "https://iso-week.gumballtools.com/api/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add com-gumballtools-iso-week -t streamable-http -u 'https://iso-week.gumballtools.com/api/mcp'
```

### Other

```json
{
  "mcpServers": {
    "com-gumballtools-iso-week": {
      "type": "http",
      "url": "https://iso-week.gumballtools.com/api/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-09-25 (score 74, 0)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

### 2026-09-24 (score 74, +1)

No change was recorded against any check on this day. Stability & Change Management went from 57 to 60. That category is still filling its 30-day observation window: 17 days of observed history at the previous scan, 18 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-22 (score 73, +1)

No change was recorded against any check on this day. Stability & Change Management went from 50 to 53. That category is still filling its 30-day observation window: 15 days of observed history at the previous scan, 16 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-20 (score 72, +1)

No change was recorded against any check on this day. Stability & Change Management went from 43 to 47. That category is still filling its 30-day observation window: 13 days of observed history at the previous scan, 14 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-17 (score 71, +1)

No change was recorded against any check on this day. Stability & Change Management went from 33 to 37. That category is still filling its 30-day observation window: 10 days of observed history at the previous scan, 11 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-15 (score 70, +1)

No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-13 (score 69, +1)

No change was recorded against any check on this day. Stability & Change Management went from 20 to 23. That category is still filling its 30-day observation window: 6 days of observed history at the previous scan, 7 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-11 (score 68, +1)

No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.

## MCP tools (1)

### `run` (~549 tokens)

ISO Week Number

Converts between calendar dates and ISO 8601 week numbers, in either direction, and reports how many weeks an ISO year has.

Use this whenever a date needs to be expressed as a week number, or a week number needs to be turned back into a date — sprint planning, report periods, "week 37" style scheduling, or reconciling two systems that disagree about what week it is.

DO NOT compute this yourself with day-of-year divided by 7. ISO 8601 week 1 is defined as the week (Monday-Sunday) containing the year's first Thursday, not the week containing January 1st. This has two consequences that are easy to get wrong from memory: late-December dates can belong to ISO week 1 of the NEXT calendar year, and early-January dates can belong to ISO week 52 or 53 of the PREVIOUS calendar year. A year has 53 ISO weeks (not the usual 52) exactly when January 1 is a Thursday, or the year is a leap year and January 1 is a Wednesday — a rule nobody carries around, and getting it wrong produces a plausible-looking but incorrect week number with no visible sign of the error.

Input is a single string, and the shape of the string picks the operation:
  "2027-01-01"   a calendar date (YYYY-MM-DD)      -> returns its ISO year, week, and weekday
  "2026-W53"     an ISO week, no weekday given      -> returns the Monday of that week
  "2026-W53-5"   an ISO week and weekday (1-7, Mon-Sun) -> returns that exact date
  "2026"         a bare 4-digit year                -> returns whether it has 52 or 53 ISO weeks

Refuses rather than guesses: slash-separated dates like "03/04/2025" are rejected as ambiguous (month/day vs day/month), two-digit years are rejected as a guess, invalid calendar dates (Feb 30) are rejected, and a week number beyond what that ISO year actually has (e.g. week 53 of a 52-week year) is rejected and told how many weeks that year has.

Input parameters:

- `input` (string, required): A calendar date "YYYY-MM-DD" (e.g. "2027-01-01"), an ISO week "YYYY-Www" or "YYYY-Www-D" where D is 1-7 for Monday-Sunday (e.g. "2026-W53-5"), or a bare 4-digit year (e.g. "2026") to ask how many ISO…

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/com-gumballtools-iso-week/api-mcp#diagnostics

## Score history

- 2026-09-25: 74
- 2026-09-24: 74
- 2026-09-23: 73
- 2026-09-22: 73
- 2026-09-21: 72
- 2026-09-20: 72
- 2026-09-19: 71
- 2026-09-18: 71
- 2026-09-17: 71
- 2026-09-16: 70
- 2026-09-15: 70
- 2026-09-14: 69
- 2026-09-13: 69
- 2026-09-12: 68
- 2026-09-11: 68
- 2026-09-10: 67
- 2026-09-09: 67
- 2026-09-08: 66
- 2026-09-07: 66
- 2026-09-06: 65

## Common questions

### What is the ISO Week Number MCP server?

ISO Week Number is an MCP server listed in the public MCP registry as com.gumballtools/iso-week. ISO 8601 week numbers: date to week, week to date, weeks-per-year. This page covers its hosted endpoint (https://iso-week.gumballtools.com/api/mcp).

### Is the ISO Week Number MCP server safe to use?

ISO Week Number scores 74 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the ISO Week Number MCP server expose?

ISO Week Number exposes 1 tool: run. Their descriptions and schemas cost roughly 549 tokens of context every time the server is loaded.

### Does the ISO Week Number MCP server require authentication?

No. We connected to ISO Week Number without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the ISO Week Number MCP server still maintained?

ISO Week Number is still listed as active in the MCP registry. We last reached this channel on 25 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- Remote endpoint: https://iso-week.gumballtools.com/api/mcp
- Repository: https://github.com/bwalvoord/gumball
- Website: https://iso-week.gumballtools.com/
- Changelog RSS feed: https://verifymcp.io/servers/com-gumballtools-iso-week/api-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/com-gumballtools-iso-week/api-mcp.json
- HTML version of this page: https://verifymcp.io/servers/com-gumballtools-iso-week/api-mcp