Designs an interface other people will depend on — REST endpoints, RPC methods, library functions, CLI commands, event payloads. Use this whenever the user is adding a public endpoint, designing a library's surface, defining a message contract, or asking how something should be called. Also use before implementing anything other teams or external users will consume, because the cost of changing it later is the whole point. For implementing against an existing interface, use…
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
# API design
An API is a promise. Implementation is cheap to change; a published interface is not, because
every caller has to move with you. Design it as though you cannot change it, because roughly
speaking you cannot.
**Design from the caller's side.** Write the code that calls your API before you write the API.
If that code is awkward, the design is wrong, and you have found out in two minutes instead of
after three teams have integrated.
## 1. Model the domain, not the storage
The most common failure is exposing your database schema through HTTP. It couples every consumer
to your internal structure, so a routine table split becomes everyone's migration.
Name resources and operations in the language your users use, not your tables. If a caller
must understand your persistence model to use the API, the abstraction has already failed.
**Done when:** you could change the storage layer without touching the interface.
## 2. Make the wrong call impossible
Design so misuse does not compile, or fails immediately and clearly:
- **Required things are required.** Not optional-with-a-runtime-check.
- **Enums over free strings** for anything with a fixed set of values.
…
The line at the top of this page pins the label git:20260828.866dec6, 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.
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 (4803 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
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Source
GitHub
okhp3/skillz · 3 stars · license MIT · pushed 2026-11-06 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_hheumofth62rvx3e
GET https://markdownregistry.com/api/v1/resolve?ref=okhp3/skillz/api-design
GET https://markdownregistry.com/api/v1/blob/d04116d3be9f5d85483feb86a428ee78506cfa740cd5a511cdad1d3fcbdc5024
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.
okhp3/skillz · .agents/skills/architecture-decision-records/SKILL.md · Write and maintain Architecture Decision Records (ADRs) following best practices for technical decision documentation…
okhp3/skillz · .agents/skills/frontend-design/SKILL.md · Create distinctive, production-grade frontend interfaces with high design quality. Use this skill when the user asks to…
okhp3/skillz · .agents/skills/okhp3-artifact-validation/SKILL.md · Validate a project change, draft, research packet, skill, promotion package, or handoff before it is treated as…
okhp3/skillz · .agents/skills/okhp3-as-is-process-capture/SKILL.md · Capture and normalise a current-state process description into a structured as-is process YAML with stable step…
okhp3/skillz · .agents/skills/okhp3-brand-style-registry/SKILL.md · OverKill Hill P³ visual style registry and application workflow. Use when a user wants to extract a reusable brand…
okhp3/skillz · .agents/skills/okhp3-capture-intake/SKILL.md · Preserve one raw idea, file, link, transcript, or request in a project inbox with provenance and minimal handling. Use…
okhp3/skillz · .agents/skills/okhp3-custom-gpt-builder/SKILL.md · Build, audit, and improve OpenAI Custom GPTs with production-grade methodology. Use this skill when the user asks to…
okhp3/skillz · .agents/skills/okhp3-custom-gpt-readiness/SKILL.md · Assess an incomplete or newly proposed Custom GPT concept for build readiness. Use when a user has a GPT idea, partial…
okhp3/skillz · .agents/skills/okhp3-decision-model-authoring/SKILL.md · Author and validate decision models from PNS decision points using DMN-aligned rule tables. Use this skill when the PNS…
okhp3/skillz · .agents/skills/okhp3-elicitation-interviews/SKILL.md · Plan and facilitate structured elicitation sessions using BABOK v3 interview and workshop techniques. Use this skill…
affaan-m/ecc · docs/es/skills/api-design/SKILL.md · Patrones de diseño REST API incluyendo nomenclatura de recursos, códigos de estado, paginación, filtrado, respuestas de…
ericrisco/rsc-harness · skills/api-design/SKILL.md · Use when settling the contract of an API you expose, before implementation: resources/URLs, REST vs GraphQL…
yonatangross/orchestkit · plugins/ork/skills/api-design/SKILL.md · API wire contracts for REST and GraphQL: resource shape, versioning and deprecation, RFC 9457 errors, OpenAPI. Use when…
