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/kbwen/agentic-os/api-designnpx skills add KbWen/agentic-os --skill api-designgit clone --depth 1 https://github.com/KbWen/agentic-osWhat 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 | $0.00017 | $0.01023 |
| Opus 5 | $0.00009 | $0.00511 |
| Sonnet 5 | $0.00003 | $0.00205 |
| Haiku 4.5 | $0.00002 | $0.00102 |
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 3d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- api-design — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Design
When to Apply
- Classification: feature, architecture-change, hotfix (if touching API endpoints)
- Phase: /implement (design & build), /review (compliance check), /test (contract verification)
- Trigger: Task involves creating, modifying, or deprecating API endpoints
Conventions
Customize after /app-init: Replace these generic conventions with your project's ADR decisions.
Endpoint Naming
- Use nouns for resources, not verbs:
GET /usersnotGET /getUsers - Plural resource names:
/users,/orders,/products - Nested resources for relationships:
/users/:id/orders - Use kebab-case for multi-word paths:
/order-items
HTTP Methods
| Action | Method | Success Status | Idempotent |
|---|---|---|---|
| List | GET | 200 | Yes |
| Get one | GET | 200 | Yes |
| Create | POST | 201 | No |
| Full update | PUT | 200 | Yes |
| Partial update | PATCH | 200 | No |
| Delete | DELETE | 204 | Yes |
Error Response Format
{
"error": {
"code": "VALIDATION_ERROR",
"message": "Email is required",
"details": {
"field": "email",
"constraint": "required"
}
}
}
Standard Error Codes
| HTTP Status | When | Error Code Pattern |
|---|---|---|
| 400 | Invalid input | VALIDATION_ERROR, INVALID_FORMAT |
| 401 | Not authenticated | UNAUTHORIZED |
| 403 | Not permitted | FORBIDDEN |
| 404 | Resource not found | NOT_FOUND |
| 409 | Conflict (duplicate) | CONFLICT, DUPLICATE |
| 422 | Business rule violation | UNPROCESSABLE |
| 429 | Rate limited | RATE_LIMITED |
| 500 | Server error | INTERNAL_ERROR |
Pagination
{
"data": [...],
"pagination": {
"total": 100,
"page": 1,
"per_page": 20,
"has_next": true
}
}
Versioning
- URL path versioning:
/api/v1/users - Breaking changes require new version
- Deprecation: add
Sunsetheader with date, keep old version for N months
Input Validation
- Validate at the controller/route level BEFORE business logic
- Return ALL validation errors at once (batch), not one at a time
- Sanitize strings: trim whitespace, escape HTML where applicable
- Enforce max lengths on all string fields
What ships with it
1 file 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.
- 3d ago First seen · 127 lines · 17 tokens per session scan A 3bb02b810098
api-design is a skill published in the GitHub repository KbWen/agentic-os (149 stars, last pushed 9d ago), licensed MIT. It adds 17 tokens to every session and 1,023 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 2026-08-30.
Other skills, from other repositories
orloj-generator
Interactive scaffold generator for Orloj multi-agent systems. Use this skill whenever someone wants to create, set up, scaffold, bootstrap, or generate an Orloj agent system, pipeline, swarm, or hierarchy. Also trigger when users mention "orlojctl init", ask how to get started with Orloj, want to build a multi-agent…
muster-frappe-metadata
Design, generate, review, apply, and roll back Frappe or ERPNext metadata changes through Muster. Use for DocTypes, child tables, custom fields, property setters, workflows, roles, permissions, reports, print formats, web pages, workspaces, fixtures, patches, or installed-app compatibility.
muster-frappe-release
Build, seed, deploy, break, measure, and prove a Muster Frappe release. Use for bench or site setup, migrations, realistic ERPNext data, role matrices, browser/mobile QA, performance and recovery tests, release evidence, Frappeverse demos, or normal-speed presentation video.
muster-frappe-security
Threat-model and negatively verify Muster integrations with Frappe OAuth, multi-tenancy, RBAC, field permissions, agent delegation, channels, secrets, approvals, and audit logs. Use for identity linking, site registration, Telegram onboarding, policy changes, permission tests, or security release gates.
muster-frappe-workflows
Design and implement durable multi-step Muster workflows for Frappe with agent, subagent, and nested task graphs. Use for workflow definitions, planning, delegation, tool policies, approvals, retries, schedules, triggers, artifacts, dynamic page creation, or Claude-style universal JS and JSON automation.
muster-frappe-orchestrator
Coordinate end-to-end Muster automation work across Frappe or ERPNext architecture, metadata, UI, workflows, security, testing, deployment, and evidence. Use for cross-cutting features, production plans, multi-agent delivery, or work that spans Muster core and a Frappe app.