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/saitarrun/devforge-ai/api-designnpx skills add saitarrun/Devforge-ai --skill api-designgit clone --depth 1 https://github.com/saitarrun/Devforge-aiWhat 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 | $0.00048 | $0.00675 |
| Opus 5 | $0.00024 | $0.00338 |
| Sonnet 5 | $0.00010 | $0.00135 |
| Haiku 4.5 | $0.00005 | $0.00068 |
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 2d 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.
How it starts
The opening of the file, as written. The whole thing — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill: API Design
Design APIs as contracts. Versions matter. Backward compatibility is non-negotiable.
REST Principles
- Noun-based URLs:
/usersnot/getUsers - HTTP methods: GET (read), POST (create), PUT (update), DELETE (remove)
- Status codes: 200 (OK), 201 (created), 400 (bad request), 401 (auth), 404 (not found), 500 (error)
- Consistency: Same patterns across all endpoints
Versioning Strategy
URL path (explicit, clear):
GET /api/v1/users # v1 API
GET /api/v2/users # v2 API (breaking change)
Header (less visible, prefer path):
GET /api/users
Header: API-Version: 2
Breaking Changes = Major Version
v1.0 → v2.0: User response format changed
v1.1 → v1.2: New optional field added (backward-compatible)
v1.0 → v1.1: Bug fix (patch)
API Contract (OpenAPI/Swagger)
paths:
/users/{id}:
get:
summary: Get user
parameters:
- name: id
in: path
required: true
schema: { type: string }
responses:
'200':
description: User found
content:
application/json:
schema:
$ref: '#/components/schemas/User'
'404':
description: Not found
Error Responses
{
"error": "not_found",
"message": "User not found",
"code": 404,
"details": {
"resource": "user",
"id": "user-123"
}
}
Rate Limiting
Header: X-RateLimit-Limit: 1000
Header: X-RateLimit-Remaining: 999
Header: X-RateLimit-Reset: 1640000000
Pagination
GET /users?page=2&page_size=10
Response:
{
"items": [...],
"total": 245,
"page": 2,
"page_size": 10,
"has_next": true
}
Deprecation Plan
1. Announce: Email, docs, API response header
2. Timeline: 6 months before removal
3. Header: X-API-Warn: "endpoint deprecated, use /v2/..."
4. Support: v1 and v2 endpoints run in parallel
5. Remove: After timeline expires
Status: Ready for API design
Best for: API contracts, versioning, error handling
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.
- 2d ago First seen · 114 lines · 48 tokens per session scan A eb0f1879990c
api-design is a skill published in the GitHub repository saitarrun/Devforge-ai (5 stars, last pushed 19d ago), licensed Apache-2.0. It adds 48 tokens to every session and 675 once invoked, about $0.0002 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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