Spec Driven Development
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
Runs on your computer
Hydroxyl
Overview
Description from the maker (original English)
Local stdio MCP server: publication figures, structure checks and conversions for AI assistants
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
- UsageiVery new↓ 55/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).
- You fill in yourself:
HYDROXYL_EDITOR_URL
You need
- npmNode.js installed (for the npx command)
Which app do you use?
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": {
"hydroxyl": {
"command": "npx",
"args": [
"-y",
"hydroxyl-mcp"
],
"env": {
"HYDROXYL_EDITOR_URL": "your-value"
}
}
}
}Run this in your terminal
claude mcp add hydroxyl --env HYDROXYL_EDITOR_URL=your-value -- npx -y hydroxyl-mcpFill in the empty values before running it.
Or copy the settings yourself
Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"hydroxyl": {
"command": "npx",
"args": [
"-y",
"hydroxyl-mcp"
],
"env": {
"HYDROXYL_EDITOR_URL": "your-value"
}
}
}
}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.
Or copy the settings yourself
Paste into .vscode/mcp.json in your project
{
"servers": {
"hydroxyl": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"hydroxyl-mcp"
],
"env": {
"HYDROXYL_EDITOR_URL": "your-value"
}
}
}
}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.
Values you fill in
HYDROXYL_EDITOR_URLenvEditor that editor_link points at (default https://hydroxyl.app/editor/)
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 9, 2026
- ✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account trebeljahr, 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 18648 servers in this category
- Published to the registry more recently than 59% of the other 18648 servers in this category
- Basic checks equal to or better than 100% of the other 18648 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 Hydroxyl 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 (0.1.0) reached the registry 32 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, arr-mcp
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
Remote Desktop Commander
Remote Desktop Commander: use files, terminal and processes on your own computers from any AI app.
Runs in the cloud✓ desktopcommander.app
arr-mcp
One server, 40 tools, the whole media stack: *arrs, Jellyfin, Plex, Seerr, Cleanuparr, downloaders
Runs on your computer
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.
hydroxyl-mcp
hydroxyl-mcp is a local Model Context Protocol server. An assistant such as Claude Desktop can use it to draw a structure as a journal figure, check it, and convert it. It runs on your machine over stdio and makes no network calls. Structures you send go to your assistant's provider, never to us.
It has five tools:
| Tool | Input | Output |
|---|---|---|
render_figure | a structure; views; width (single, double or cm); png or svg | the figure, its printed size, its label size, and a warning for text under 8 pt |
check_structure | a structure | the valence and drawing issues the editor flags, each with its one-click fixes |
describe | a structure | formula, molecular weight, exact mass, net charge, CIP labels |
convert | a structure | a molfile or a canonical SMILES |
editor_link | a structure | a link that opens the structure in the editor |
A structure is one of smiles, molfile, or name (a compound from the editor's insert box, such as caffeine).
Add it to your MCP client; npx fetches the hydroxyl-mcp package from npm (Node.js 22 or newer). For Claude Desktop, edit claude_desktop_config.json (Settings → Developer → Edit Config) and restart the app:
{"mcpServers": { "hydroxyl": { "command": "npx", "args": ["-y", "hydroxyl-mcp"] } } }
Other clients that start stdio servers take the same command and arguments. For Claude Code:
claude mcp add hydroxyl -- npx -y hydroxyl-mcpeditor_link points at https://hydroxyl.app/editor/. Set HYDROXYL_EDITOR_URL in the server's environment to link to a local or self-hosted editor instead.
The editor itself is at hydroxyl.app; source at github.com/trebeljahr/hydroxyl.app.
Licence
MIT. The package depends on RDKit (BSD-3-Clause) and resvg-wasm (MPL-2.0), and ships the Arimo font (OFL-1.1, text in dist/arimo-OFL.txt).