Colregs MCP

Name: Colregs MCP
Author: mark-brannan

by mark-brannanversion 0.0.7i★ –iRuns on your computer

Registry nameio.github.mark-brannan/colregs-mcp

Install

Overview

Description from the maker (original English)

Not for navigation. Pre-release preview: COLREGS Part C night lights, international text only.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiEarly↓ 498/wk · ★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
The registry lists no key to fill in.

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "colregs": {
      "command": "npx",
      "args": [
        "-y",
        "colregs-mcp"
      ]
    }
  }
}

Run this in your terminal

claude mcp add colregs -- npx -y colregs-mcp

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "colregs": {
      "command": "npx",
      "args": [
        "-y",
        "colregs-mcp"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "colregs": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "colregs-mcp"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 8, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account mark-brannan, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

More stars than 0% of the other 18584 servers in this category
Published to the registry more recently than 92% of the other 18584 servers in this category
Basic checks equal to or better than 100% of the other 18584 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Colregs MCP safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.0.7) reached the registry 3 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, aamio rendezvous

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

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Remote Desktop Commander

Remote Desktop Commander: use files, terminal and processes on your own computers from any AI app.

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Runs in the cloud✓ desktopcommander.app

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aamio rendezvous

Meet an agent you have not met, exchange messages that expire, and prove it happened. No account.

by aamio.atEarlyUpdated today

Runs in the cloud✓ aamio.at

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

colregs-mcp

[!WARNING]

Not for navigation. This is a preview (0.0.x) built on pre-release

rule data. Do not use its output to decide what to do on the water.

The tool surface will change without notice.

An MCP server that answers questions under the COLREGS. Every answer carries its paragraph cites and the verbatim rule text those cites resolve to, so a language model cannot quietly simplify it. The rules are evaluated by colregs-engine; this package only decides how the answer is written down.

Try it

Claude Code:

claude mcp add colregs -- npx -y colregs-mcp

Claude connector directory: in Claude, open Settings → Connectors, search for COLREGS and click Connect. No configuration is needed.

Any other MCP client: command npx, arguments -y colregs-mcp, no environment.

From a clone:

git clone https://github.com/mark-brannan/colregs-mcp && cd colregs-mcp && npm install && npm run build

then command node, argument /absolute/path/to/colregs-mcp/dist/cli.js.

Tools

tool	input	returns
`evaluate`	`circumstances`	one evaluation: `appraisal`, `signals`, `indicated`, `compliance`
`rule_text`	`cite`	the verbatim text of a COLREGS paragraph
`light`	`id`	one light's definition: colour, character, arc, placement

evaluate

circumstances is the whole picture one vessel is in: self (her own facts), others (each other vessel, with what is known or observed of her) and conditions (visibility, environment). One call evaluates the picture; the response carries four readings of it.

`signals`: every complete, lawful set of lights self may show. Each light carries its modality (shall, may, shall-if-practicable) and the paragraph that prescribes it.
`appraisal`: what the Rules require of self on her own, and then against each other vessel: the kind of encounter, whether risk of collision is asserted, and each vessel's role (stand-on, give-way, shall-not-impede).
`indicated`: for each other vessel, what her observed lights, shapes and sounds indicate she could be.
`compliance`: over a track of circumstances sampled through time, one verdict per vessel per obligation that attached: kept, breached or pending.

Every id travels with its paragraph cite, and cited_paragraphs holds the verbatim text of every paragraph the response cites. The input vocabulary is generated from the colregs data package at startup. A key or value outside it is an error, never an empty answer.

rule_text

Takes a paragraph path such as 25(b) or 26(c)(i), a bare rule number such as 25 for every paragraph of that rule, or a range such as 24(a)(ii)-(iv). Returns the International text as transcribed from the USCG amalgamated Navigation Rules, with its source and retrieval date.

light

Takes a light id as it appears in a response, such as light:sidelights or light:all_round. Returns the Rule 21 definition: colour, character, arc in degrees and placement.

Example

A 12 m sloop under way, alone.

"circumstances": { "self": { "fact:propulsion": "propulsion:sail", "fact:activity": "activity:none", "fact:position": "position:underway", "fact:length_m": 11.6 } } }

Trimmed response:

"colregs": { "version": "0.3.4" }, "signals": { "applied": [ { "id": "rule:25a", "cite": "25(a)", "modality": "modality:shall" }, { "id": "rule:25b", "cite": "25(b)", "modality": "modality:may" }, { "id": "rule:25c", "cite": "25(c)", "modality": "modality:may" } ], "lawful_displays": { "count": 3, "relation": "any_one_of", "options": [ { "option": 1, "of": 3, "lights": [ { "light": "light:sidelights", "modality": "modality:shall", "prescribed_by": { "id": "rule:25a", "cite": "25(a)" } }, { "light": "light:sternlight", "modality": "modality:shall", "prescribed_by": { "id": "rule:25a", "cite": "25(a)" } } ] }, { "option": 2, "of": 3, "...": "..." }, { "option": 3, "of": 3, "...": "..." } ] }, "modality_key": { "modality:shall": "mandatory", "modality:may": "permitted alternative" }, "cited_paragraphs": { "25(a)": "A sailing vessel underway shall exhibit: (i) sidelights; (ii) a sternlight.", "25(b)": "…", "25(c)": "…" } }, "appraisal": { "self": { "...": "..." }, "others": [] }, "indicated": [] }

The sloop has three lawful displays, because the Rules give her the choice and nothing in the input settles it.

docs/demo.md puts the same question to the same model with and without this server and shows both answers as captured.

Response shape

Three properties hold for every response:

Cited, verbatim. Every entry id travels with its paragraph cite, and cited_paragraphs holds the text of every paragraph cited. The only sentences in a response are the Rules' own.
Modality per light. shall, may and shall-if-practicable are kept on each light, not summarised per display. modality_key is a one-line glossary of the modalities the response uses.
Plural by construction. lawful_displays opens with count and relation before any lights appear, and each option numbers itself n of count. There is no top-level lights field to mistake for the answer.

A vessel that lawfully shows nothing gets one empty display, not an error. An error is reserved for input outside the vocabulary.

Every response carries colregs.version. The server refuses to start if its own copy of colregs and the engine's are different releases.

Dependencies

colregs-engine and colregs are installed from GitHub main, not from npm releases; the lockfile pins the commit. Both must resolve the same release.

Privacy Policy

The server collects nothing. It runs as a local stdio process, answers from the colregs data package installed beside it, and makes no network request of its own. There is no telemetry, no logging of what it is asked, and no account. The only network transaction is the install itself, which is npm's.

Releasing

Automatic from the release tag: npm and the MCP registry. The by-hand steps (Smithery, the Claude directory plugin bundle) are in docs/releasing.md.

Licence

AGPL-3.0-only. The fitness-for-navigation disclaimer in colregs carries over.

Colregs MCP

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

aamio rendezvous

README from the maker

colregs-mcp

Try it

Tools

evaluate

rule_text

light

Example

Response shape

Dependencies

Privacy Policy

Releasing

Licence