Spec Driven Development
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
Runs on your computer
RFC lookup
Overview
Description from the maker (original English)
40x fewer tokens while reading the RFC corpus and flag obsoleted specs.
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↓ 78/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
- PyPIPython’s uv installed (for the uvx 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": {
"rfc-ai-tooling": {
"command": "uvx",
"args": [
"mcp-server-rfc"
]
}
}
}Run this in your terminal
claude mcp add rfc-ai-tooling -- uvx mcp-server-rfcOr copy the settings yourself
Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"rfc-ai-tooling": {
"command": "uvx",
"args": [
"mcp-server-rfc"
]
}
}
}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": {
"rfc-ai-tooling": {
"type": "stdio",
"command": "uvx",
"args": [
"mcp-server-rfc"
]
}
}
}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 shbernal, 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 18474 servers in this category
- Published to the registry more recently than 82% of the other 18474 servers in this category
- Basic checks equal to or better than 100% of the other 18474 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 RFC lookup 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 (0.6.1) reached the registry 9 days ago.
Which apps can use it?
Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Python (uv) on your computer.
What can I use instead?
In the same category: Spec Driven Development, Remote Desktop Commander, Thalovant 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
Thalovant MCP
Connect MCP clients to Thalovant control-plane and hub runtime APIs over stdio or Streamable HTTP.
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.
mcp-server-rfc
An MCP server that reads the RFC corpus with 40x fewer tokens and flags obsoleted specs.
{"mcpServers": { "rfc": { "command": "uvx", "args": ["mcp-server-rfc"] } } }
No clone, no virtualenv, no path. That is the whole installation. Your client spawns the server on your machine and talks to it over stdin and stdout.
A client showing the server as connected has not necessarily used it, and a model will happily answer an RFC question from memory instead. On Claude Desktop the per-server log records only the handshake, so it cannot tell you either way — docs/desktop-verification.md says where the evidence actually is.
Tools
| Tool | What it does |
|---|---|
search_rfcs | Search titles, or the full text of every RFC, ranked by section, if the section index is present |
list_sections | An RFC's headings with line numbers — the cheap first call |
get_rfc | Read one section, or a line range |
With the section index, a full-text query is words, and each result is one section ranked by BM25, carrying the section number to pass to get_rfc and the line that best matches. Without it, full-text search falls back to rg or grep over a synced mirror, where the query is a literal string and results are whole RFCs; regex=true opts into pattern matching there and in titles. The payload names the backend in tool. Title results put current RFCs before superseded ones, so a page cut short at limit keeps the document you want rather than the one it replaced.
get_rfc refuses any read of more than 1500 lines that is not a named section, answering with its size and a pointer to list_sections rather than filling the context with a specification the model had one question about; a start_line of 1 does not get around it. full=true overrides it. A section you asked for by name is never refused: list_sections reports how long each one is, and max_lines caps any read, so the choice is informed rather than blocked.
Every response carries a banner with the RFC's status and, when it applies, a warning that it has been superseded:
RFC 2616 — Hypertext Transfer Protocol -- HTTP/1.1 [DRAFT STANDARD]!! OBSOLETED BY: RFC 7230, 7231, 7232, 7233, 7234, 7235
That warning is the reason to use this rather than let a model fetch rfc-editor.org itself. Models cite dead specifications with great confidence.
Full-text search
Works with no setup, fetching documents on demand. Full-text search additionally needs the section index, which the user downloads from a shell:
uvx mcp-server-rfc sync --indexAbout 270 MB from this project's GitHub releases, checked against its published SHA-256. It ranks sections by BM25 and serves every read from disk, so the server stops fetching from the RFC Editor. uvx mcp-server-rfc sync instead copies the corpus as 512 MB of text files from the RFC Editor's volunteer-run rsync mirror, which is what rg and regex=true search.
The same command that runs the server runs its CLI: sync downloads, status reports what is present, and uvx mcp-server-rfc --help covers the rest. It is also the command the server names in the error you get when full-text search is asked for without either.
Both are optional. The server deliberately does not expose a sync tool: hundreds of megabytes on someone's disk should be a person's decision, not a model's.
If an index or a mirror already exists — synced for the companion skill, say — this server picks it up automatically. It looks under the platform's data directory: $XDG_DATA_HOME/rfc-ai-tooling, or %LOCALAPPDATA%\rfc-ai-tooling on Windows, falling back to ~/.local/share/rfc-ai-tooling. Set $RFC_MIRROR to point at a non-default location — in a container with no home directory, that or --mirror is what to pass.
In a container, uvx on the host would write to the wrong disk. Keep the mirror in a named volume, fill it through the image, and set $RFC_CLI so the server's errors name that command instead of uvx mcp-server-rfc:
docker build -t mcp-server-rfc mcp/docker run --rm -it -v rfc-mirror:/mirror mcp-server-rfc mcp-server-rfc sync --index docker run --rm -i -v rfc-mirror:/mirror -e RFC_TRANSPORT=stdio \ -e RFC_CLI="docker run --rm -it -v rfc-mirror:/mirror mcp-server-rfc mcp-server-rfc" \ mcp-server-rfc
HTTP mode
The config above is the stdio transport, which needs a client that can spawn a process on your machine. A session running in the cloud — claude.ai on the web, Cowork — cannot, and no configuration fixes that. For those, the server has to be deployed somewhere they can reach:
mcp-server-rfc --transport http --host 0.0.0.0 --port 8080RFC_TRANSPORT, HOST and PORT are read from the environment too. The repository carries a Dockerfile and a fly.toml that do this. No public instance of this server exists and none is planned — if you want one, you host it, and you should put authentication in front of it, since the server has none and would otherwise be an open proxy to a volunteer-run mirror.
Full-text search works hosted only where the section index is on the server's disk (sync --index there). Without it, a hosted instance returns an error saying so instead of silently answering a title search. The obsolescence banner, section reads and the unscoped-read guard work either way, because they need only the 2 MB RFC index.
If your client has a shell
Use the skill instead — Claude Code, Codex CLI, OpenClaw, Cursor and Zed all qualify. It does the same things with fewer moving parts and gives the agent ripgrep over the corpus:
npx skills add shbernal/rfc-ai-tooling # from the repo, into .claude/skills/clawhub install @shbernal/rfc-lookup # or the last released version
This server is for clients that give the model no shell of its own. Claude Desktop is the clearest case: its chat cannot run a command on your machine, but it will spawn this server there.
Source, issues and the skill: https://github.com/shbernal/rfc-ai-tooling
MIT.