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/monkilabs/opencastle/api-patternsnpx skills add monkilabs/opencastle --skill api-patternsgit clone --depth 1 https://github.com/monkilabs/opencastleWhat 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 | $0.00055 | $0.00401 |
| Opus 5 | $0.00028 | $0.00200 |
| Sonnet 5 | $0.00011 | $0.00080 |
| Haiku 4.5 | $0.00006 | $0.00040 |
Grade A, and why
api-patterns scanned grade A with 1 finding 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
Smoke-test a new route with `curl -fsS "http://localhost:3000/api/<name>?query=test"`. What it actually says
API Patterns
Project-specific config: .opencastle/stack/api-config.md.
Architecture
| Layer | Use for |
|---|---|
| Server Actions (preferred) | mutations, form submissions, data writes, auth |
Route Handlers (route.ts) |
analytics, autocomplete, external integrations |
| Proxy layer | IP rate limiting, fingerprinting, bot detection |
Route files live at app/api/<name>/route.ts or app/<segment>/route.ts.
Rules
- Validate every input with Zod on the server at the top of the handler; 400 on parse failure.
- Response envelope:
{ "data": ..., "meta": { "total": 42, "page": 1 } } - Error shape:
{ "error": { "code": "VALIDATION_ERROR", "message": "...", "details": [...] } }— never leak stack traces. Status codes: 400, 401, 403, 404, 422, 429, 500. - RESTful nouns, versioned:
/api/v1/places/:slug. Add fields only — never remove or rename; deprecation headers before removal. - Pagination: cursor-based preferred; params
limit,cursor,sort,order. - Retry external API calls twice with linear backoff (500 ms × attempt).
- Rate-limit public endpoints; set
Cache-ControlandETag/If-None-Match.
Smoke-test a new route with curl -fsS "http://localhost:3000/api/<name>?query=test".
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 · 31 lines · 55 tokens per session scan A 682e3e7b4022
api-patterns is a skill published in the GitHub repository monkilabs/opencastle (61 stars, last pushed 4d ago), licensed MIT. It adds 55 tokens to every session and 401 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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