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.
npx agentmods add skills/kraitdev/skill.md/api-design-restnpx skills add KraitDev/skiLL.Md --skill api-design-restgit clone --depth 1 https://github.com/KraitDev/skiLL.MdWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00015 | $0.01631 |
| Opus 5 | $0.00008 | $0.00816 |
| Sonnet 5 | $0.00003 | $0.00326 |
| Haiku 4.5 | $0.00002 | $0.00163 |
Grade A, and why
api-design-rest 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.
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.
How it starts
The opening of the file, as written. The whole thing — 157 lines — stays where its author put it; the contents beside it link to each section on GitHub.
RESTful API Design
Purpose
REST APIs MUST be intuitive, predictable, and semantically correct. This skill ensures APIs use HTTP methods correctly, communicate errors clearly via standard formats, and maintain consistency across resources so clients can interact with them reliably without surprise behavior.
When to use
- Building a new backend service exposing resources
- Adding a new domain entity to an existing API
- Creating integration endpoints for third-party partners
- Designing webhooks or callback mechanisms
- Standardizing an inconsistent API across a microservices architecture
When NOT to use
- Error handling specifics (use Error Handling Architecture skill)
- API authentication/authorization (separate concern)
- Rate limiting or throttling strategies (separate concern)
- GraphQL design (different paradigm)
Inputs required
- Existing API codebase or documented business entities
- HTTP framework (Express, Django, FastAPI, etc.)
- OpenAPI/Swagger familiarity preferred
Workflow
- Identify Resources: Map business entities to Plural Nouns (users, orders, invoices, not getUsers)
- Assign Verbs: Map CRUD operations to HTTP methods: GET (read), POST (create), PUT (replace), PATCH (update), DELETE (remove)
- Design URL Hierarchy: Nest resources logically but NO DEEPER than 2 levels (e.g.,
/users/{id}/ordersONLY) - Standardize Responses: All success payloads wrapped consistently; all errors use RFC 7807 format
- Add Pagination: For collection endpoints, REQUIRE
limitandoffset(or cursor-based pagination) - Version the API: Use
/v1/prefix or header-based versioning from day one - Document with OpenAPI: Generate OpenAPI schema automatically or maintain it in sync
Rules
- MUST use HTTP status codes semantically (see failure conditions below)
- MUST NOT use verbs in URLs (no
GET /getUsers) - MUST NOT nest resources beyond 2 levels deep
- MUST use lowercase URLs with hyphens for multi-word resource names
- MUST require API versioning
- MUST return RFC 7807 problem details for ALL errors
- MUST paginate collection responses
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.
- yesterday First seen · 157 lines · 15 tokens per session scan A 566a6d5d1eed
api-design-rest is a skill published in the GitHub repository KraitDev/skiLL.Md (7 stars, last pushed 2mo ago), licensed MIT. It adds 15 tokens to every session and 1,631 once invoked, about $0.0001 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.
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