api-patterns

A guide for designing APIs, the interfaces that let software systems exchange requests and data, using REST, GraphQL, or tRPC.

In plain words
What is it for?
Use it to choose an API style, design resources and payloads, plan versioning and pagination, add authentication or rate limits, and review API security.
Why use it?
It helps keep endpoints, responses, authentication, errors, and limits consistent as an API grows.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/phuonghx/aim-cli/api-patterns
Any agent
npx skills add phuonghx/aim-cli --skill api-patterns
Clone the repo
git clone --depth 1 https://github.com/phuonghx/aim-cli

Made for: Claude Code, Codex.

Per session 86 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 724 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00086 $0.00724
Opus 5 $0.00043 $0.00362
Sonnet 5 $0.00017 $0.00145
Haiku 4.5 $0.00009 $0.00072

Measured yesterday against content hash 645d8aab5a56, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-patterns 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 yesterday.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/api_validator.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.

aim/templates/aim-agents/skills/api-patterns/SKILL.md · 82 lines

How it starts

The opening of the file, as written. The whole thing — 82 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Patterns

Reason about API design from first principles. The goal is judgment for your situation, not a template to paste.

How to use this skill

These notes are split into focused files. Open only the one that maps to the question in front of you instead of reading everything at once. The table below is your index.


File index

File Covers Open it when
api-style.md Picking REST vs GraphQL vs tRPC Deciding the paradigm
rest.md Resource names, verbs, status codes Laying out a REST surface
response.md Payload shape, errors, paging Shaping what you return
graphql.md Schema modeling, fit, hardening Weighing GraphQL
trpc.md Typed TS client/server Full-stack TypeScript work
versioning.md URI / header / query schemes Planning for change
auth.md Tokens, sessions, OAuth, keys Picking how callers prove identity
rate-limiting.md Quotas and throttling Shielding the service
documentation.md OpenAPI and reference docs Writing the docs
security-testing.md OWASP API risks, authz checks Reviewing for security

Sibling skills

If you also need Reach for
To actually build the endpoints @[skills/nodejs-best-practices]
To model the underlying data @[skills/database-design]
A deeper security pass @[skills/vulnerability-scanner]

Pre-flight checklist

Run through these before committing to a design:

  • Who calls this API, and from where? (asked, not assumed)
  • Paradigm chosen for this problem (REST / GraphQL / tRPC)
  • One response shape, applied everywhere
  • A story for how the API changes over time
  • Identity and access model decided
  • Throttling thought through
  • A plan for keeping docs alive

Traps to avoid

Stop doing this:

  • Reaching for REST reflexively on every project
  • Naming endpoints after actions (e.g. /fetchUsers)
  • Letting each route return a differently shaped body
  • Leaking stack traces or DB errors to callers
  • Shipping with no throttling at all

Read the full file on GitHub · 82 lines

Files

What ships with it

11 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. yesterday First seen · 82 lines · 86 tokens per session scan A 645d8aab5a56

Subscribe to this mod's changes

api-patterns is a skill published in the GitHub repository phuonghx/aim-cli (1 stars, last pushed 2mo ago), licensed MIT. It adds 86 tokens to every session and 724 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories

hs-release

Cut a core Hindsight release (vX.Y.Z) and open the changelog + blog PR. Use when asked to cut/start a release, bump the version, or publish a new Hindsight version.

vectorize-io/hindsight · 45 tokens

hindsight-local

Store user preferences, learnings from tasks, and procedure outcomes. Use to remember what works and recall context before new tasks. (user).

vectorize-io/hindsight · 32 tokens

research-repository

Build a repository that makes findings findable, reusable, and cumulative across teams. Use when the same research keeps getting redone. For synthesising one study, use affinity-diagram.

Owl-Listener/designer-skills · 43 tokens

design-negotiation

Advocate for design quality, scope, and timeline with partners and leadership using evidence and shared goals. Use in the conversation itself. For the commercial vocabulary behind it, use business-design (ux-strategy).

Owl-Listener/designer-skills · 48 tokens

user-persona

Build research-grounded personas with goals, frustrations, and behavioural patterns. Use when decisions need a consistent user reference. For one session's emotional snapshot use empathy-map; for motivation framing use jobs-to-be-done.

Owl-Listener/designer-skills · 50 tokens

version-control-strategy

Define version control for design files, components, and libraries — branching, naming, and release. Use when file history is chaotic. For design system contribution rules, use design-system-governance (design-systems).

Owl-Listener/designer-skills · 50 tokens