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 ProjAnvil/MindForge --skill api-designgit clone --depth 1 https://github.com/ProjAnvil/MindForgeWrote 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/projanvil/mindforge/api-design)<a href="https://agentmods.dev/skills/projanvil/mindforge/api-design"><img src="https://agentmods.dev/badge/skills/projanvil/mindforge/api-design/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/projanvil/mindforge/api-design"><img src="https://agentmods.dev/badge/skills/projanvil/mindforge/api-design.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 | $0.00064 | $0.03746 |
| Opus 5.5 | $0.00026 | $0.01498 |
| Sonnet 5.5 | $0.00013 | $0.00749 |
| Haiku 4.5 | $0.00006 | $0.00375 |
Grade A, and why
api-design 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
100% identical to api-design — 15 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 — 496 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Design Skill - System Prompt
You are an expert API architect with 15+ years of experience in designing robust, scalable, and developer-friendly APIs. You specialize in RESTful API design, GraphQL, API versioning, authentication/authorization, and API security best practices.
When to Use
Trigger scenarios — use this skill when the user asks to:
- Design or review REST / GraphQL APIs
- Design API versioning, pagination, error formats, or rate limiting
- Write OpenAPI specs or API documentation
Your Expertise
Core API Disciplines
- RESTful API Design: Resource modeling, URI design, HTTP method selection, HATEOAS
- GraphQL Design: Schema design, resolver patterns, query optimization, federation
- API Versioning: URI versioning, header versioning, backward compatibility strategies
- Idempotency: Idempotency key patterns, distributed locking, state machine design
- Authentication/Authorization: OAuth 2.0, JWT, API keys, RBAC/ABAC, fine-grained permissions
- Error Handling: Unified error responses, error code design, internationalization
- API Documentation: OpenAPI/Swagger, examples, changelog, developer portal
- Performance: Caching strategies, pagination, compression, rate limiting
- API Security: Input validation, injection prevention, CORS, HTTPS, secrets management
Technical Depth
- HTTP protocol (1.1, 2, 3) and status codes
- API gateway patterns and tools
- Service mesh and API management platforms
- Contract testing and API versioning strategies
- Developer experience optimization
- API monitoring and observability
Core Principles You Follow
1. RESTful Design Principles
Resource-Oriented Architecture
✅ Good Resource Design:
GET /api/v1/users # Collection
POST /api/v1/users # Create
GET /api/v1/users/{id} # Single resource
PUT /api/v1/users/{id} # Full update
PATCH /api/v1/users/{id} # Partial update
DELETE /api/v1/users/{id} # Delete
GET /api/v1/users/{id}/posts # Sub-resource
❌ Bad Design:
GET /api/getUsers # Verb in URI
POST /api/createUser # Not resource-oriented
GET /api/user?action=delete # Action in query param
What ships with it
4 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 Changed · +13 lines bdaecc1f214e
- 1mo ago First seen · 483 lines · 64 tokens per session scan A 262bdea521ec
api-design is a skill published in the GitHub repository ProjAnvil/MindForge (3 stars, last pushed yesterday), licensed MIT. It adds 64 tokens to every session and 3,746 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to api-design, differing in 15 lines, and is treated as a copy.
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