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 skills add eric861129/SKILLS_All-in-one --skill api-designergit clone --depth 1 https://github.com/eric861129/SKILLS_All-in-oneWrote 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.
[](https://agentmods.dev/skills/eric861129/skills_all-in-one/api-designer)<a href="https://agentmods.dev/skills/eric861129/skills_all-in-one/api-designer"><img src="https://agentmods.dev/badge/skills/eric861129/skills_all-in-one/api-designer/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.
<a href="https://agentmods.dev/skills/eric861129/skills_all-in-one/api-designer"><img src="https://agentmods.dev/badge/skills/eric861129/skills_all-in-one/api-designer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00039 | $0.01825 |
| Opus 5 | $0.00019 | $0.00912 |
| Sonnet 5 | $0.00008 | $0.00365 |
| Haiku 4.5 | $0.00004 | $0.00183 |
Grade A, and why
api-designer 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 6d ago.
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.
This is a copy
94% identical to api-designer — 2 lines 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.
How it starts
The opening of the file, as written. The whole thing — 218 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Designer
Senior API architect specializing in REST and GraphQL APIs with comprehensive OpenAPI 3.1 specifications.
Core Workflow
- Analyze domain — Understand business requirements, data models, and client needs
- Model resources — Identify resources, relationships, and operations; sketch entity diagram before writing any spec
- Design endpoints — Define URI patterns, HTTP methods, request/response schemas
- Specify contract — Create OpenAPI 3.1 spec; validate before proceeding:
npx @redocly/cli lint openapi.yaml - Mock and verify — Spin up a mock server to test contracts:
npx @stoplight/prism-cli mock openapi.yaml - Plan evolution — Design versioning, deprecation, and backward-compatibility strategy
Reference Guide
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| REST Patterns | references/rest-patterns.md |
Resource design, HTTP methods, HATEOAS |
| Versioning | references/versioning.md |
API versions, deprecation, breaking changes |
| Pagination | references/pagination.md |
Cursor, offset, keyset pagination |
| Error Handling | references/error-handling.md |
Error responses, RFC 7807, status codes |
| OpenAPI | references/openapi.md |
OpenAPI 3.1, documentation, code generation |
Constraints
MUST DO
- Follow REST principles (resource-oriented, proper HTTP methods)
- Use consistent naming conventions (snake_case or camelCase — pick one, apply everywhere)
- Include comprehensive OpenAPI 3.1 specification
- Design proper error responses with actionable messages (RFC 7807)
- Implement pagination for all collection endpoints
- Version APIs with clear deprecation policies
- Document authentication and authorization
- Provide request/response examples
MUST NOT DO
- Use verbs in resource URIs (use
/users/{id}, not/getUser/{id}) - Return inconsistent response structures
- Skip error code documentation
- Ignore HTTP status code semantics
- Design APIs without a versioning strategy
- Expose implementation details in the API surface
- Create breaking changes without a migration path
- Omit rate limiting considerations
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.
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.
- 6d ago First seen · 218 lines · 39 tokens per session scan A 185d4b3c6cae
api-designer is a skill published in the GitHub repository eric861129/SKILLS_All-in-one (52 stars, last pushed 4mo ago), licensed MIT. It adds 39 tokens to every session and 1,825 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to api-designer, differing in 2 lines, and is treated as a copy.
Other skills, from other repositories
architect
This skill should be used when the user asks to "design system architecture", "evaluate microservices vs monolith", "create architecture diagrams", "analyze dependencies", "choose a database", "plan for scalability", "make technical decisions", or "review system design".
backend
This skill should be used when the user asks to "design REST APIs", "optimize database queries", "implement authentication", "build microservices", "review backend code", "set up GraphQL", "handle database migrations", or "load test APIs".
clerk-knowledge-patch
Use this guide when implementing, upgrading, or debugging Clerk authentication, authorization, Organizations, Billing, SDKs, components, or deployment architecture. Start with the migration notes, then open the matching reference.
apache-kafka-knowledge-patch
Use this skill when upgrading, configuring, extending, or operating Apache Kafka and its clients, Kafka Streams, Kafka Connect, MirrorMaker, KRaft, share groups, or tiered storage. Inspect the project's actual broker, client, metadata, and Java versions before applying version-dependent advice.
aspnet-core-knowledge-patch
Use this patch when implementing, reviewing, testing, or upgrading ASP.NET Core applications. Check breaking behavior first, then open only the topic references relevant to the task.
authjs-knowledge-patch
Use this patch to choose the maintained authentication path, avoid security-sensitive provider mistakes, and apply current Auth.js integration patterns. Read the topic reference before changing an affected flow; the quick reference prioritizes breaking behavior, security updates, and common implementation work.