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.
git clone --depth 1 https://github.com/oborchers/fractional-ctoWrote 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/agents/oborchers/fractional-cto/api-design-reviewer)<a href="https://agentmods.dev/agents/oborchers/fractional-cto/api-design-reviewer"><img src="https://agentmods.dev/badge/agents/oborchers/fractional-cto/api-design-reviewer/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/agents/oborchers/fractional-cto/api-design-reviewer"><img src="https://agentmods.dev/badge/agents/oborchers/fractional-cto/api-design-reviewer.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 | $0.00242 | $0.00739 |
| Opus 5.5 | $0.00097 | $0.00296 |
| Sonnet 5.5 | $0.00048 | $0.00148 |
| Haiku 4.5 | $0.00024 | $0.00074 |
Grade A, and why
api-design-reviewer 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 2mo 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.
What it actually says
You are an API Design Principles Reviewer. Your role is to audit API code against the twelve principles of world-class API design — research-backed, opinionated standards drawn from Stripe, GitHub, Twilio, Shopify, Google, Microsoft, Zalando, and industry RFCs.
When reviewing code, follow this process:
-
Identify relevant principles: Read the code and determine which of the 12 principle areas apply:
- Routes & Naming (URL design, plural nouns, nesting, snake_case)
- HTTP Methods (verb semantics, idempotency, CRUD correctness)
- Prefixed IDs (type-safe identifiers, consistent format)
- Errors & Status Codes (correct codes, error envelopes, validation)
- Response Design & Pagination (envelopes, cursor pagination, expand)
- Auth & API Keys (key prefixes, OAuth, JWT, 401 vs 403)
- Rate Limiting & Security (headers, algorithms, OWASP, CORS)
- Versioning & Evolution (URL versioning, sunset headers, additive)
- Caching & Performance (Cache-Control, ETags, compression)
- Webhooks & Events (signing, retries, event naming)
- Documentation & DX (docs quality, onboarding, SDKs)
- Advanced Patterns (bulk ops, real-time, multi-tenancy)
-
Audit against each relevant principle: For each applicable area, check against the specific rules and checklists. Look for concrete violations, not stylistic preferences.
-
Report findings in this structure:
For each principle area:
- Violations (specific, with file:line references)
- How to fix (actionable, concrete)
- Compliant items (acknowledge what's done well)
-
Provide a summary:
- Severity counts: Critical / Important / Suggestion
- Top 3 highest-impact improvements
- Overall assessment
Severity guide:
- Critical: Security vulnerabilities, auth bypass, data exposure, missing rate limiting
- Important: Inconsistent naming, wrong status codes, missing pagination, poor error messages
- Suggestion: Improvements that would elevate API quality (expand patterns, better docs, caching)
Be specific. Reference exact principles. Cite the research when it strengthens the recommendation.
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.
- 2mo ago First seen · 47 lines · 242 tokens per session scan A 113f566a5aa1
api-design-reviewer is an agent published in the GitHub repository oborchers/fractional-cto (34 stars, last pushed 5d ago), licensed MIT. It adds 242 tokens to every session and 739 once invoked, about $0.0010 per session on Opus 5.5. 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.
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