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postels-law SKILL.md skillA

postels-law from the-artificer-of-ciphers-llc/skills-from-the-artificer is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.

Install it, pinned

mdr add the-artificer-of-ciphers-llc/skills-from-the-artificer/postels-law@git:20260530.3e17152

Pins git:20260530.3e17152 in mdr.lock. Pin the fingerprint instead.

Audit grade: A, 17 of 17 checks passed
Kind: SKILL.md skill
Repository: the-artificer-of-ciphers-llc/skills-from-the-artificer
Path: postels-law/SKILL.md
Versions recorded: 1
Latest version: git:20260530.3e17152, committed May 30, 2026
Size: 4,249 bytes
Repository stars: 6
License: MIT

Apply Postel's Law when designing APIs, data interchange formats, network protocols, input validation, or any interface that will receive data from other systems or users. Trigger on phrases like "how strict should our API be?", "should we accept slightly malformed input?", "what should we send vs. accept?", "how do we handle unexpected fields?", or any question about the balance between strictness and permissiveness in an interface design. Postel's Law is a foundational principle of robust…

Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.

What the file says

# Postel's Law (Robustness Principle)

> "Be conservative in what you send, liberal in what you accept."
> — Jon Postel, RFC 760, 1980

## The core idea

When building systems that communicate with other systems, Postel recommended:
- **Send only well-formed, minimal, correct data.** Don't rely on the other side tolerating your quirks.
- **Accept data that is slightly off.** Be forgiving of minor variations, extra fields, or slightly non-standard inputs from senders.

This principle shaped the early internet. HTML parsers that accepted malformed tags, TCP stacks that handled variations in packet formatting — the early web grew partly because implementors were lenient about what they accepted.

## The case for it

**Real-world senders make mistakes.** Other systems, other developers, other versions of software — they will send you data that is slightly wrong. If you reject anything imperfect, you become brittle and hard to integrate with.

**Interoperability requires tolerance.** When you have many producers of data and many consumers, allowing slightly varied input enables the ecosystem to grow. Strict rejection creates integration friction.
…

Read the whole file at its exact version.

How to install

The exact contents, by fingerprint

mdr add the-artificer-of-ciphers-llc/skills-from-the-artificer/postels-law@sha256:17fbd0e6a2e4738c

The line at the top of this page pins the label git:20260530.3e17152, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.

Badge

[![mdr](https://markdownregistry.com/badge/art_4n43qsclhdc23byc.svg)](https://markdownregistry.com/a/art_4n43qsclhdc23byc)

5 badge image fetches in 30 days. What the badge shows.

Versions

The registry has recorded 1 version of this file, committed on May 30, 2026.

version	committed	commit	size	audit
git:20260530.3e17152 latest	2026-05-30	3e17152	4,249 B	A	view

Audit of the latest version

A 17 of 17 checks passed. Fixed automatic checks with no AI involved, so the same checks give the same answer every run.

pass: Frontmatter block present
pass: Frontmatter declares a name
pass: Frontmatter declares a description
pass: Size between 200 bytes and 200 KB (4249 bytes)
pass: No zero-width or bidi control characters
pass: No instruction hidden inside an HTML comment
pass: No link to an exfiltration or paste host
pass: No credential-shaped string
pass: No instruction to send local credentials anywhere
pass: No text hidden with inline styles
pass: No prompt-injection phrasing
pass: No curl or wget piped into a shell
pass: No recursive delete of root, home or parent
pass: No instruction to read or print local credentials
pass: No base64 blob over 200 characters
pass: No link to a raw IP address
pass: No script tag

Source

GitHub

the-artificer-of-ciphers-llc/skills-from-the-artificer · 6 stars · license MIT · pushed 2026-11-08 · branch main

API

GET https://markdownregistry.com/api/v1/artifacts/art_4n43qsclhdc23byc
GET https://markdownregistry.com/api/v1/resolve?ref=the-artificer-of-ciphers-llc/skills-from-the-artificer/postels-law
GET https://markdownregistry.com/api/v1/blob/17fbd0e6a2e4738c045d4956e3440adc4733d423dc472f9baba77116066a1f9d

Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.

Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.

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