Api Design

Organization

DevelopersGlobal

api-design

Design stable, versioned, self-documenting APIs. Easy to use correctly, hard to use incorrectly. Apply Hyrum's Law from day one.

Overview

Publisher	DevelopersGlobal
Repository	`ai-agent-skills`
Skill name	`api-design`
Stars	212
Forks	33
Bundled files	Instructions only
License	MIT
Links	Skill source Repository Homepage

Markdown instructions
A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.
Works with any LLM
AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.
Self-contained
Everything the model needs lives in the instructions — no extra files to sync.
Open source
Published by DevelopersGlobal on GitHub. Read the source before you install it.

Installation

Install the Api Design AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

Open the app and go to Plugins → Skills.
Choose "Install from GitHub".
Paste the skill folder URL below and confirm.
https://github.com/DevelopersGlobal/ai-agent-skills/tree/main/skills/api-design
Enable the skill in any chat where you want it available.

Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills

git clone --depth 1 https://github.com/DevelopersGlobal/ai-agent-skills.git /tmp/ai-agent-skills
mkdir -p .claude/skills
cp -r /tmp/ai-agent-skills/skills/api-design .claude/skills/api-design

Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Api Design in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Api Design on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Api Design is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

Loaded only when it is needed
The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.
Switch models mid-chat
Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

Overview

APIs are contracts. Once published, every behavior — documented or not — becomes something users depend on (Hyrum's Law). This skill enforces the discipline of designing APIs that are stable, self-documenting, and difficult to misuse.

When to Use

Creating any public API endpoint
Designing function/library APIs
Extending or versioning existing APIs

Process

Step 1: Design the Interface First

Write the usage examples before writing the implementation.
Ask: Is this easy to use correctly? Is it hard to use incorrectly?
Apply the principle of least surprise — the API should do what it looks like it does.
Design for the caller, not the implementer.

Verify: You can write 3 example usages without looking at the implementation.

Step 2: Apply Hyrum's Law

Every observable behavior of your API will be depended upon by someone.
Document what IS and IS NOT guaranteed:
- Stable: return type, error codes, semantic behavior
- Unstable: response time, field ordering, internal implementation
Be conservative in what you expose — you can always add, never remove.

Verify: Every public field and behavior is either documented as stable or marked as internal.

Step 3: Versioning Strategy

Version from day one: /api/v1/, Content-Type: application/vnd.myapi.v1+json
Breaking changes require a new version.
Maintain old versions for at least 6 months with deprecation notices.
Additive changes (new optional fields) are non-breaking.

Verify: API version is in the URL or headers. Deprecation policy is documented.

Step 4: Self-Documentation

Every endpoint: purpose, inputs, outputs, error codes — documented.
Error messages tell the caller what went wrong AND how to fix it.
Schema validation on all inputs with meaningful error messages.
OpenAPI/Swagger spec generated (not hand-written).

Verify: A new developer can use the API from documentation alone, without reading source code.

Common Rationalizations (and Rebuttals)

Excuse	Rebuttal
"We'll document it later"	Undocumented APIs become black boxes. Document as you build.
"We can break it, it's internal"	Internal APIs become external. Design them well from the start.
"Versioning is premature"	Retrofitting versioning into an unversioned API is painful. Start versioned.

Verification

Interface designed before implementation
Stable vs. unstable behaviors documented
Versioning strategy in place
All endpoints documented (OpenAPI/Swagger)
Error messages actionable
Breaking vs. non-breaking changes policy defined

Frequently asked questions

What does the Api Design AI skill do?

Design stable, versioned, self-documenting APIs. Easy to use correctly, hard to use incorrectly. Apply Hyrum's Law from day one.

Why use Api Design on TypingMind?

Because you install it once and use it with any model. Api Design is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Api Design in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/DevelopersGlobal/ai-agent-skills/tree/main/skills/api-design. TypingMind reads its SKILL.md and installs it as a skill you can enable per chat.

Which AI models can use Api Design?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Api Design?

As many as you like. As long as a model supports skills, you can use Api Design with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Api Design AI skill free?

Yes. It is published on GitHub by DevelopersGlobal under the MIT license. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

View all

Writing Skills

obra

CommunityPopular

Use when creating new skills, editing existing skills, or verifying skills work before deployment

Skill Host Compat

Lint ECC skills for Codex/Cursor-safe frontmatter and Claude-only substitutions before a skill PR.

Brand Voice

Build a source-derived writing style profile from real posts, essays, launch notes, docs, or site copy, then reuse that profile across content, outreach, and social workflows. Use when the user wants…

Competitive Platform Analysis

affaan-m

CommunityPopular

Use when scoping a competitive landscape — identifying, categorising, and score-filtering a competitor set before any benchmarking begins. Decides who counts as a competitor, which tier they belong…

Overview

Installation

Install in TypingMind

Install in another agent

Use it in TypingMind

Works with any AI model

Skill instructions

Overview

When to Use

Process

Step 1: Design the Interface First

Step 2: Apply Hyrum's Law

Step 3: Versioning Strategy

Step 4: Self-Documentation

Common Rationalizations (and Rebuttals)

Verification

References

Frequently asked questions

Related AI Skills

Set up your own AI workspace now