api-design-principles

api-design-principles is a skill for Claude Code, Codex from hybridlabor-api/bdb-dev-optimized-agent-skills. It costs 34 tokens per session (365 once invoked), scanned A, a copy of api-design-principles, Apache-2.0.

A guide to designing REST and GraphQL APIs, the interfaces that let applications exchange data and actions.

In plain words
What is it for?
Use it to design or review new APIs, improve existing interfaces, document them, or plan a REST-to-GraphQL migration.
Why use it?
It helps keep APIs understandable and consistent by addressing resources or types, errors, authentication, pagination, versioning, and consumer needs.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to design or review new APIs, improve existing interfaces, document them, or plan a REST-to-GraphQL migration.

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Install with agentmods
npx agentmods add skills/hybridlabor-api/bdb-dev-optimized-agent-skills/api-design-principles
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add hybridlabor-api/bdb-dev-optimized-agent-skills --skill api-design-principles
Clone the repo
git clone --depth 1 https://github.com/hybridlabor-api/bdb-dev-optimized-agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for api-design-principles

README.md
[![agentmods](https://agentmods.dev/badge/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/api-design-principles/github.svg)](https://agentmods.dev/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/api-design-principles)
Your own site
<a href="https://agentmods.dev/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/api-design-principles"><img src="https://agentmods.dev/badge/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/api-design-principles/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for api-design-principles

Your own site · 80×15
<a href="https://agentmods.dev/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/api-design-principles"><img src="https://agentmods.dev/badge/skills/hybridlabor-api/bdb-dev-optimized-agent-skills/api-design-principles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 365 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 95% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00034 $0.00365
Opus 5 $0.00017 $0.00182
Sonnet 5 $0.00007 $0.00073
Haiku 4.5 $0.00003 $0.00036

Measured 5d ago against content hash 494cebe326ff, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

api-design-principles scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (assets/rest-api-template.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

95% identical to api-design-principles — 1 line differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/global_config/api-design-principles/SKILL.md · 47 lines

What it actually says

API Design Principles

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

Use this skill when

  • Designing new REST or GraphQL APIs
  • Refactoring existing APIs for better usability
  • Establishing API design standards for your team
  • Reviewing API specifications before implementation
  • Migrating between API paradigms (REST to GraphQL, etc.)
  • Creating developer-friendly API documentation
  • Optimizing APIs for specific use cases (mobile, third-party integrations)

Do not use this skill when

  • You only need implementation guidance for a specific framework
  • You are doing infrastructure-only work without API contracts
  • You cannot change or version public interfaces

Instructions

  1. Define consumers, use cases, and constraints.
  2. Choose API style and model resources or types.
  3. Specify errors, versioning, pagination, and auth strategy.
  4. Validate with examples and review for consistency.

Refer to resources/implementation-playbook.md for detailed patterns, checklists, and templates.

Resources

  • resources/implementation-playbook.md for detailed patterns, checklists, and templates.

Limitations

  • Use this skill only when the task clearly matches the scope described above.
  • Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 47 lines · 34 tokens per session scan A 494cebe326ff

Subscribe to this mod's changes

api-design-principles is a skill published in the GitHub repository hybridlabor-api/bdb-dev-optimized-agent-skills (6 stars, last pushed 4d ago), licensed Apache-2.0. It adds 34 tokens to every session and 365 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to api-design-principles, differing in 1 line, and is treated as a copy.

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