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 lfyxhappy/lfcode --skill api-designergit clone --depth 1 https://github.com/lfyxhappy/lfcodeWrote 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/lfyxhappy/lfcode/api-designer)<a href="https://agentmods.dev/skills/lfyxhappy/lfcode/api-designer"><img src="https://agentmods.dev/badge/skills/lfyxhappy/lfcode/api-designer.svg" alt="Measured on agentmods" 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 | $0.00080 | $0.00319 |
| Opus 5 | $0.00040 | $0.00160 |
| Sonnet 5 | $0.00016 | $0.00064 |
| Haiku 4.5 | $0.00008 | $0.00032 |
Grade A, and why
api-designer 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.
What it actually says
API Designer
Make an interface understandable and durable for callers before code commits to a wire format.
Workflow
- Identify callers, operators, stored data, generated clients, and existing conventions that constrain the interface.
- Define operations, input and output schemas, defaults, validation, authorization, errors, pagination or limits, and idempotency behavior.
- Specify compatibility and evolution rules, including versioning, deprecation, retries, ordering, and migration of persisted payloads.
- Model sensitive fields, audit requirements, rate or resource limits, and observable failure behavior.
- Write representative contract examples and focused success, invalid-input, authorization, conflict, and compatibility tests.
Boundaries
- Do not confuse API design with API review: use this skill to establish a contract, then use API review to audit an implemented contract.
- Do not expose credentials, personal data, internal-only endpoints, or real production payloads in examples.
- Do not make wire-breaking changes or publish a contract without explicit user authorization.
Completion Check
Report the proposed contract, affected consumers, compatibility policy, tests, migration requirements, and decisions still needing approval.
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 · 27 lines · 80 tokens per session scan A 068d470df7a6
api-designer is a skill published in the GitHub repository lfyxhappy/lfcode (2 stars, last pushed 4d ago), licensed MIT. It adds 80 tokens to every session and 319 once invoked, about $0.0004 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 2026-09-05.
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