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 mehdiozdemir/awesome-agent-skills --skill api-designergit clone --depth 1 https://github.com/mehdiozdemir/awesome-agent-skillsWrote 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/mehdiozdemir/awesome-agent-skills/api-designer)<a href="https://agentmods.dev/skills/mehdiozdemir/awesome-agent-skills/api-designer"><img src="https://agentmods.dev/badge/skills/mehdiozdemir/awesome-agent-skills/api-designer/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/skills/mehdiozdemir/awesome-agent-skills/api-designer"><img src="https://agentmods.dev/badge/skills/mehdiozdemir/awesome-agent-skills/api-designer.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 | $0.00052 | $0.04929 |
| Opus 5.5 | $0.00021 | $0.01972 |
| Sonnet 5.5 | $0.00010 | $0.00986 |
| Haiku 4.5 | $0.00005 | $0.00493 |
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 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.
How it starts
The opening of the file, as written. The whole thing — 906 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Designer Skill
This skill helps design, review, and implement APIs following industry best practices. Use this whenever you need to create new APIs, review existing API designs, generate specifications, or improve API developer experience.
API Design Principles
1. REST API Fundamentals
| Principle | Description |
|---|---|
| Resource-Oriented | URLs represent resources, not actions |
| Stateless | Each request contains all needed information |
| Uniform Interface | Consistent patterns across endpoints |
| HATEOAS | Responses include navigation links |
| Cacheable | Responses indicate cacheability |
2. HTTP Methods
| Method | Purpose | Idempotent | Safe | Request Body |
|---|---|---|---|---|
GET |
Read resource | ✅ | ✅ | ❌ |
POST |
Create resource | ❌ | ❌ | ✅ |
PUT |
Replace resource | ✅ | ❌ | ✅ |
PATCH |
Partial update | ❌ | ❌ | ✅ |
DELETE |
Remove resource | ✅ | ❌ | ❌ |
HEAD |
Get headers only | ✅ | ✅ | ❌ |
OPTIONS |
Get allowed methods | ✅ | ✅ | ❌ |
3. HTTP Status Codes
Success (2xx):
| Code | Meaning | Use Case |
|---|---|---|
200 |
OK | Successful GET, PUT, PATCH |
201 |
Created | Successful POST |
202 |
Accepted | Async operation started |
204 |
No Content | Successful DELETE |
Client Errors (4xx):
| Code | Meaning | Use Case |
|---|---|---|
400 |
Bad Request | Invalid input/validation error |
401 |
Unauthorized | Missing/invalid authentication |
403 |
Forbidden | Valid auth but insufficient permissions |
404 |
Not Found | Resource doesn't exist |
405 |
Method Not Allowed | Wrong HTTP method |
409 |
Conflict | Duplicate/conflict with current state |
422 |
Unprocessable Entity | Semantic validation error |
429 |
Too Many Requests | Rate limit exceeded |
Server Errors (5xx):
| Code | Meaning | Use Case |
|---|---|---|
500 |
Internal Server Error | Unexpected server error |
502 |
Bad Gateway | Upstream service error |
503 |
Service Unavailable | Maintenance/overload |
504 |
Gateway Timeout | Upstream timeout |
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 · 906 lines · 52 tokens per session scan A 1f6b75db5eca
api-designer is a skill published in the GitHub repository mehdiozdemir/awesome-agent-skills (2 stars, last pushed 9mo ago), licensed MIT. It adds 52 tokens to every session and 4,929 once invoked, about $0.0002 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 2026-08-31.
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