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Agent skill

API Design Principles

by coco-research in coco-research/coco

A skill your agent uses when designing a new REST or GraphQL API, reviewing an API spec before implementation, setting team API standards, or migrating REST to GraphQL.

Custom licenceAuto-check passedBackend & APIs

Install API Design Principles

skills CLI
$ npx skills add coco-research/coco --skill api-design-principles -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install coco-research/coco api-design-principles --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/coco-research/coco.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/api-design-principles .claude/skills/api-design-principles && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
api-design-principles
GitHub stars
503
Token cost
~3.4k tokens
SKILL.md length
453 words
Files
5 (incl. references, assets)
Skills in repo
63
Repo updated
First seen
Licence
Custom licence

At a glance

A skill your agent uses when designing a new REST or GraphQL API, reviewing an API spec before implementation, setting team API standards, or migrating REST to GraphQL.

  • Works in 3 steps: RESTful Design Principles → GraphQL Design Principles → API Versioning Strategies
  • Designing a new REST
  • SKILL.md covers When to Use This Skill, Core Concepts, REST API Design Patterns and GraphQL Design Patterns, plus 3 more sections
  • Runs Python scripts from its folder

What it does

API Design Principles is an agent skill from coco-research/coco. Use when designing a new REST or GraphQL API, reviewing an API spec before implementation, setting team API standards, or migrating REST to GraphQL. Covers resources, HTTP semantics, pagination, error handling, and pitfalls.

Its SKILL.md is about 3.4k tokens, which your agent loads only when the skill is triggered. The skill folder holds 6 other files, including reference files and assets (for example `assets/api-design-checklist.md`, `assets/rest-api-template.py` and `references/graphql-schema-design.md`).

It sits in Backend & APIs, covering GraphQL, API design and OpenAPI specifications. It works with GraphQL. The repository describes itself as: CoCo Super Intelligence is the orchestration layer that turns Claude Code, Cursor, or Codex into an engineering department: a routed advisory board, 226 skills, 386 commands…

When your agent uses it

  • Designing a new REST
  • Reviewing an API spec before implementation
  • Setting team API standards
  • Migrating REST to GraphQL

Example prompts

  • “/api-design-principles”

Requirements

  • Python 3

Workflow steps

3 steps, taken from the step headings in SKILL.md.

  1. RESTful Design Principles
  2. GraphQL Design Principles
  3. API Versioning Strategies

What it can do on your machine

Read from SKILL.md and the folder at commit d79d33a. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Ships script files (Python), which the agent can run.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

API Design Principles loads about 3.4k tokens when it runs, and up to ~7.5k if it reads all its reference files. Until then it costs about 62 tokens; SKILL.md has 453 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~62
When it runs · the whole SKILL.md, loaded when a task matches
~3.4k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~7.5k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 453 words (~3,397 tokens).

“Master REST and GraphQL API design principles to build intuitive, scalable, and maintainable APIs that delight developers and stand the test of time.”

— opening of SKILL.md by coco-research, Custom licence
name
api-design-principles
domain
engineering

Read the full SKILL.md on GitHub

Files

SKILL.md and 4 other files (references, assets) in skills/api-design-principles of coco-research/coco.

  • SKILL.md
  • assets/api-design-checklist.md
  • assets/rest-api-template.py
  • references/graphql-schema-design.md
  • references/rest-best-practices.md

Open the folder on GitHubat commit d79d33a

Compare with similar skills

API Design Principles next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

API Design Principles compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
API Design Principles this skillcoco-research/coco503—~3.4kAutomated safety check: PassCustom licence
API DesignerJeffallan/claude-skills12k1 repos~2kAutomated safety check: PassMIT
API Designyonatangross/orchestkit290—~2.9kAutomated safety check: PassMIT
API Contract Detectionprime-radiant-inc/greenfield292—~4.2kAutomated safety check: PassApache-2.0
API Contract Designrsmdt/the-startup557—~1.1kAutomated safety check: PassMIT
API Designericrisco/rsc-harness174—~3.1kAutomated safety check: PassMIT

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Works with

Categories

Questions about API Design Principles

What does API Design Principles do?

A skill your agent uses when designing a new REST or GraphQL API, reviewing an API spec before implementation, setting team API standards, or migrating REST to GraphQL. API Design Principles is an agent skill from coco-research/coco. Use when designing a new REST or GraphQL API, reviewing an API spec before implementation, setting team API standards, or migrating REST to GraphQL.

When should I use API Design Principles?

API Design Principles fits situations like: designing a new REST; reviewing an API spec before implementation; setting team API standards; migrating REST to GraphQL.

How do I install API Design Principles in Claude Code?

Run `npx skills add coco-research/coco --skill api-design-principles -a claude-code`. Or copy the skill folder (skills/api-design-principles in coco-research/coco) into .claude/skills/api-design-principles in your project. Claude Code loads it when a task matches its description.

How do I install API Design Principles in Codex?

Run `npx skills add coco-research/coco --skill api-design-principles -a codex`. Or copy the skill folder (skills/api-design-principles in coco-research/coco) into .agents/skills/api-design-principles in your project. Codex loads it when a task matches its description.

Can I use API Design Principles in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add coco-research/coco --skill api-design-principles -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/api-design-principles, .gemini/skills/api-design-principles, .github/skills/api-design-principles and .opencode/skills/api-design-principles in your project.

What does API Design Principles need to run?

Going by SKILL.md and its folder, API Design Principles needs Python for the scripts in its folder. Our summary lists: Python 3.

Does API Design Principles access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is API Design Principles safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does API Design Principles use?

API Design Principles has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.

How many tokens does API Design Principles use?

About 3.4k tokens (SKILL.md is roughly 14k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 4.1k tokens, read only when the agent opens those files.

What are the alternatives to API Design Principles?

Skills that share tags, products or a category with API Design Principles: API Designer (Jeffallan/claude-skills, 12k stars), API Design (yonatangross/orchestkit, 290 stars), API Contract Detection (prime-radiant-inc/greenfield, 292 stars) and API Contract Design (rsmdt/the-startup, 557 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains API Design Principles?

coco-research (a GitHub user) maintains it in coco-research/coco, which has 503 GitHub stars. The repository holds 63 skills in this directory. The repository was last updated on October 9, 2026.

Source: coco-research/coco on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.