# Plumbkit (remote · plumbkit.dev)

Exact utilities for agents: time zones, date math, business days, calculator, units, validation.

- Trust score: 75/100 (medium)
- Change this week: +4
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-04

## Components

- remote · `plumbkit.dev`: 75/100 (this document), [markdown](https://verifymcp.io/servers/dev-plumbkit-plumbkit/plumbkit.md), [page](https://verifymcp.io/servers/dev-plumbkit-plumbkit/plumbkit)

## Channel facts

- Endpoint: `https://plumbkit.dev/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.0.0`

## 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 2026-11-04.

- **Endpoint Security**: 63/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one.
  - HTTPS enforcement could not be verified: the plaintext port answered with HTTP 405, which proves neither a plaintext path nor enforcement.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - 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**: 67/100
  - AI-judged instruction clarity (good).
  - Context-footprint check failed: tool/resource definitions use about 2418 tokens (~151/item across 16 items; 16 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 70/100
  - Stability observed for 21 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 95/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 86% 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 16 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 17 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

## Install

### How do I install the Plumbkit MCP server?

Plumbkit is a hosted endpoint at https://plumbkit.dev/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 dev-plumbkit-plumbkit 'https://plumbkit.dev/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "dev-plumbkit-plumbkit": {
      "url": "https://plumbkit.dev/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "dev-plumbkit-plumbkit": {
      "type": "http",
      "url": "https://plumbkit.dev/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.dev-plumbkit-plumbkit]
url = "https://plumbkit.dev/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "dev-plumbkit-plumbkit": {
      "type": "remote",
      "url": "https://plumbkit.dev/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add dev-plumbkit-plumbkit --url 'https://plumbkit.dev/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  dev-plumbkit-plumbkit:
    url: "https://plumbkit.dev/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "dev-plumbkit-plumbkit": {
      "Transport": "http",
      "Url": "https://plumbkit.dev/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add dev-plumbkit-plumbkit -t streamable-http -u 'https://plumbkit.dev/mcp'
```

### Other

```json
{
  "mcpServers": {
    "dev-plumbkit-plumbkit": {
      "type": "http",
      "url": "https://plumbkit.dev/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.

### 2026-11-04 (score 75, +1)

No change was recorded against any check on this day. Stability & Change Management went from 67 to 70. That category is still filling its 30-day observation window: 20 days of observed history at the previous scan, 21 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-11-02 (score 74, +1)

No change was recorded against any check on this day. Stability & Change Management went from 60 to 63. That category is still filling its 30-day observation window: 18 days of observed history at the previous scan, 19 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-31 (score 73, +1)

No change was recorded against any check on this day. Stability & Change Management went from 53 to 57. That category is still filling its 30-day observation window: 16 days of observed history at the previous scan, 17 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-29 (score 72, +1)

No change was recorded against any check on this day. Stability & Change Management went from 47 to 50. That category is still filling its 30-day observation window: 14 days of observed history at the previous scan, 15 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-27 (score 71, +1)

No change was recorded against any check on this day. Stability & Change Management went from 40 to 43. That category is still filling its 30-day observation window: 12 days of observed history at the previous scan, 13 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-25 (score 70, +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.

### 2026-10-22 (score 69, +1)

No change was recorded against any check on this day. Stability & Change Management went from 23 to 27. That category is still filling its 30-day observation window: 7 days of observed history at the previous scan, 8 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-10-20 (score 68, +1)

No change was recorded against any check on this day. Stability & Change Management went from 17 to 20. That category is still filling its 30-day observation window: 5 days of observed history at the previous scan, 6 at this one. The score rises as the window fills, whether or not the server changes.

## MCP tools (16)

### `current_time` (~102 tokens)

Current date and time

Returns the exact current date, time, weekday and UTC offset in any time zone. Use this whenever you need to know today's date or the current time instead of guessing — your training data does not know what day it is.

Input parameters:

- `timezone` (string): IANA time zone name, e.g. "America/New_York", "Europe/London", "Asia/Tokyo", or "UTC". Fixed offsets like "UTC+5:30" also work.

### `convert_timezone` (~216 tokens)

Convert time zones

Converts a date/time from one time zone to another, correctly handling daylight saving time. If the input already includes an offset or 'Z', from_timezone is ignored.

Input parameters:

- `datetime` (string, required): Date/time in ISO 8601 (e.g. "2026-03-08T14:30", "2026-03-08T14:30:00Z", "2026-03-08"), "YYYY-MM-DD HH:mm", a Unix timestamp in seconds or milliseconds, or "now".
- `from_timezone` (string): IANA time zone name, e.g. "America/New_York", "Europe/London", "Asia/Tokyo", or "UTC". Fixed offsets like "UTC+5:30" also work. Defaults to UTC.
- `to_timezone` (string, required): IANA time zone name, e.g. "America/New_York", "Europe/London", "Asia/Tokyo", or "UTC". Fixed offsets like "UTC+5:30" also work.

### `date_add` (~301 tokens)

Add or subtract time

Adds or subtracts a duration (years, months, weeks, days, hours, minutes, seconds) to a date/time. Use negative numbers to subtract. Calendar-aware: adding 1 month to Jan 31 gives Feb 28/29, and adding days keeps the same local clock time across daylight-saving changes.

Input parameters:

- `datetime` (string, required): Date/time in ISO 8601 (e.g. "2026-03-08T14:30", "2026-03-08T14:30:00Z", "2026-03-08"), "YYYY-MM-DD HH:mm", a Unix timestamp in seconds or milliseconds, or "now".
- `days` (number): days to add (negative to subtract)
- `hours` (number): hours to add (negative to subtract)
- `minutes` (number): minutes to add (negative to subtract)
- `months` (number): months to add (negative to subtract)
- `seconds` (number): seconds to add (negative to subtract)
- `timezone` (string): Time zone the arithmetic happens in. IANA time zone name, e.g. "America/New_York", "Europe/London", "Asia/Tokyo", or "UTC". Fixed offsets like "UTC+5:30" also work. Defaults to UTC.
- `weeks` (number): weeks to add (negative to subtract)
- `years` (number): years to add (negative to subtract)

### `date_diff` (~262 tokens)

Time between two dates

Calculates the exact time between two dates/times: a calendar breakdown (years, months, days, hours, minutes, seconds) plus totals in days, hours, minutes and seconds, and the number of calendar days. Negative if end is before start.

Input parameters:

- `end` (string, required): Date/time in ISO 8601 (e.g. "2026-03-08T14:30", "2026-03-08T14:30:00Z", "2026-03-08"), "YYYY-MM-DD HH:mm", a Unix timestamp in seconds or milliseconds, or "now".
- `start` (string, required): Date/time in ISO 8601 (e.g. "2026-03-08T14:30", "2026-03-08T14:30:00Z", "2026-03-08"), "YYYY-MM-DD HH:mm", a Unix timestamp in seconds or milliseconds, or "now".
- `timezone` (string): Time zone for inputs without an offset. IANA time zone name, e.g. "America/New_York", "Europe/London", "Asia/Tokyo", or "UTC". Fixed offsets like "UTC+5:30" also work. Defaults to UTC.

### `business_days` (~215 tokens)

Business day calculator

Works with business (working) days. mode "add": returns the date N business days after start_date (start_date itself is not counted; negative N goes backward; 0 returns start_date, or the next business day if start_date is not one). mode "count": counts business days from start_date to end_date, including both ends. Weekends default to Saturday and Sunday. Public holidays are NOT built in — pass them in "holidays".

Input parameters:

- `days` (integer): Business days to add (mode "add")
- `end_date` (string): YYYY-MM-DD (mode "count")
- `holidays` (array): Dates (YYYY-MM-DD) to treat as non-working days
- `mode` (string, required): "add" or "count"
- `start_date` (string, required): YYYY-MM-DD
- `weekend` (array): Weekend days as ISO weekday numbers (1=Monday ... 7=Sunday). Default [6, 7]. Example for Friday-Saturday weekends: [5, 6]

### `calculate` (~156 tokens)

Exact calculator

Evaluates an arithmetic expression exactly, so you don't have to do mental math. Supports + - * / % ^ (or **), parentheses, constants pi/e/tau and functions: sqrt, cbrt, abs, round(x, digits), floor, ceil, trunc, sign, ln, log(x[, base]), log10, log2, exp, pow, sin, cos, tan, asin, acos, atan, atan2, min, max, hypot, factorial. Trig uses radians. Example: "(1250 * 1.08^5) - 1250".

Input parameters:

- `decimals` (integer): Optional: round the result to this many decimal places
- `expression` (string, required): The expression to evaluate

### `convert_units` (~154 tokens)

Unit converter

Converts a value between units of length, mass, volume (US and imperial), area, speed, time, digital data (KB vs KiB, bits vs bytes), energy, pressure and temperature. Accepts common abbreviations (km, lb, fl oz, mph, °F, GiB). US customary units are used for cup/pint/quart/gallon unless you say imperial.

Input parameters:

- `from` (string, required): Unit to convert from, e.g. "mi", "pound", "°F", "GB"
- `to` (string, required): Unit to convert to, e.g. "km", "kg", "celsius", "GiB"
- `value` (number, required): The number to convert

### `text_stats` (~150 tokens)

Count characters, words and lines

Counts exactly what language models are bad at counting: characters (as humans see them), words, lines, sentences, paragraphs, UTF-8 bytes, and occurrences of a letter or substring (e.g. how many "r" in "strawberry"). Use it to check length limits (tweets, SMS, meta descriptions, form fields) before submitting text.

Input parameters:

- `case_sensitive` (boolean): For `count`. Default false.
- `count` (string): Optional letter, word or substring to count occurrences of
- `overlapping` (boolean): For `count`: count overlapping matches ("aa" in "aaa" = 2). Default false.
- `text` (string, required): The text to analyze

### `hash_text` (~76 tokens)

Hash and encode text

Computes a cryptographic hash (SHA-1, SHA-256, SHA-384, SHA-512) of text, or encodes/decodes it as Base64, Base64URL, hex or URL-encoding. Text is treated as UTF-8.

Input parameters:

- `operation` (string, required)
- `text` (string, required)

### `regex_test` (~158 tokens)

Test a regular expression

Runs a JavaScript regular expression against text and returns every match with its position and capture groups, or the text after replacement. Use it to verify a regex actually works before relying on it.

Input parameters:

- `flags` (string): Optional flags: i (ignore case), m (multiline), s (dotall), u (unicode), y (sticky). Global matching is always on.
- `max_matches` (integer): Default 100
- `pattern` (string, required): Regex pattern without slashes, e.g. "(\\d{3})-(\\d{4})"
- `replace_with` (string): Optional replacement string ($1, $<name> supported). If set, returns the replaced text too.
- `text` (string, required)

### `validate_email` (~79 tokens)

Validate an email address

Checks whether an email address is correctly formatted and returns a normalized version. Set check_dns=true to also confirm the domain exists and can receive mail (MX records). Does not send email and cannot confirm that a specific mailbox exists.

Input parameters:

- `check_dns` (boolean): Also look up the domain's mail servers. Default false.
- `email` (string, required)

### `validate_phone` (~103 tokens)

Validate and format a phone number

Validates a phone number using Google's libphonenumber rules and returns it in E.164 (+14155552671), international and national formats, plus the country and line type (mobile, fixed line, toll free...). For numbers without a +country code, pass default_country.

Input parameters:

- `default_country` (string): Two-letter country code used when the number has no "+" prefix, e.g. "US", "GB", "DE"
- `phone` (string, required)

### `validate_url` (~94 tokens)

Validate and normalize a URL

Checks that a URL is well-formed, normalizes it (lowercase host, punycode, default ports removed, spaces encoded) and splits it into parts including each query parameter. Flags common problems such as missing scheme, private/localhost addresses and credentials embedded in the URL. Does not fetch the URL.

Input parameters:

- `require_https` (boolean): Treat http:// as invalid. Default false.
- `url` (string, required)

### `validate_iban` (~61 tokens)

Validate an IBAN

Validates an International Bank Account Number: country, length for that country, and the mod-97 check digits. Returns electronic and printed formats. A valid IBAN is correctly formed; this does not confirm the account exists.

Input parameters:

- `iban` (string, required)

### `json_repair` (~88 tokens)

Fix broken JSON

Turns almost-JSON into valid JSON: removes markdown code fences, comments and trailing commas, adds missing quotes, commas and closing brackets, converts single quotes, Python True/False/None and truncated output. Returns the repaired JSON string and whether the input was already valid.

Input parameters:

- `pretty` (boolean): Indent the output. Default false.
- `text` (string, required): The broken JSON text

### `json_schema_validate` (~127 tokens)

Validate JSON against a schema

Checks a JSON value against a JSON Schema (drafts 4, 7, 2019-09 and 2020-12) and lists every violation with its location. Use it to confirm structured output or an API payload is correct before sending it. `data` and `schema` may be JSON values or JSON strings.

Input parameters:

- `data` (required): The JSON value to check (any type), or a JSON string of it
- `draft` (string): Default 2020-12
- `schema` (required): The JSON Schema (object), or a JSON string of it

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/dev-plumbkit-plumbkit/plumbkit#diagnostics

## Score history

- 2026-11-04: 75
- 2026-11-03: 74
- 2026-11-02: 74
- 2026-11-01: 73
- 2026-10-31: 73
- 2026-10-30: 72
- 2026-10-29: 72
- 2026-10-28: 71
- 2026-10-27: 71
- 2026-10-26: 70
- 2026-10-25: 70
- 2026-10-24: 69
- 2026-10-23: 69
- 2026-10-22: 69
- 2026-10-21: 68
- 2026-10-20: 68
- 2026-10-19: 67
- 2026-10-18: 67
- 2026-10-17: 66
- 2026-10-16: 66
- 2026-10-15: 65
- 2026-10-14: 65

## Common questions

### What is the Plumbkit MCP server?

Plumbkit is an MCP server listed in the public MCP registry as dev.plumbkit/plumbkit. Exact utilities for agents: time zones, date math, business days, calculator, units, validation. This page covers its hosted endpoint (https://plumbkit.dev/mcp).

### Is the Plumbkit MCP server safe to use?

Plumbkit scores 75 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 Plumbkit MCP server expose?

Plumbkit exposes 16 tools: current_time, convert_timezone, date_add, date_diff, business_days, and 11 more. Their descriptions and schemas cost roughly 2,342 tokens of context every time the server is loaded.

### Does the Plumbkit MCP server require authentication?

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

### Is the Plumbkit MCP server still maintained?

Plumbkit is still listed as active in the MCP registry. We last reached this channel on 4 November 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://plumbkit.dev/mcp
- Website: https://plumbkit.dev/
- Changelog RSS feed: https://verifymcp.io/servers/dev-plumbkit-plumbkit/plumbkit.xml
- Changelog JSON feed: https://verifymcp.io/servers/dev-plumbkit-plumbkit/plumbkit.json
- HTML version of this page: https://verifymcp.io/servers/dev-plumbkit-plumbkit/plumbkit