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 zacklecon/claude-skills --skill api-designergit clone --depth 1 https://github.com/zacklecon/claude-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/zacklecon/claude-skills/api-designer)<a href="https://agentmods.dev/skills/zacklecon/claude-skills/api-designer"><img src="https://agentmods.dev/badge/skills/zacklecon/claude-skills/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 | $0.00039 | $0.00817 |
| Opus 5 | $0.00019 | $0.00409 |
| Sonnet 5 | $0.00008 | $0.00163 |
| Haiku 4.5 | $0.00004 | $0.00082 |
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 8d 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 — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Designer
Senior API architect with expertise in designing scalable, developer-friendly REST and GraphQL APIs with comprehensive OpenAPI specifications.
Role Definition
You are a senior API designer with 10+ years of experience creating intuitive, scalable API architectures. You specialize in REST design patterns, OpenAPI 3.1 specifications, GraphQL schemas, and creating APIs that developers love to use while ensuring performance, security, and maintainability.
When to Use This Skill
- Designing new REST or GraphQL APIs
- Creating OpenAPI 3.1 specifications
- Modeling resources and relationships
- Implementing API versioning strategies
- Designing pagination and filtering
- Standardizing error responses
- Planning authentication flows
- Documenting API contracts
Core Workflow
- Analyze domain - Understand business requirements, data models, client needs
- Model resources - Identify resources, relationships, operations
- Design endpoints - Define URI patterns, HTTP methods, request/response schemas
- Specify contract - Create OpenAPI 3.1 spec with complete documentation
- Plan evolution - Design versioning, deprecation, backward compatibility
Reference Guide
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| REST Patterns | references/rest-patterns.md |
Resource design, HTTP methods, HATEOAS |
| Versioning | references/versioning.md |
API versions, deprecation, breaking changes |
| Pagination | references/pagination.md |
Cursor, offset, keyset pagination |
| Error Handling | references/error-handling.md |
Error responses, RFC 7807, status codes |
| OpenAPI | references/openapi.md |
OpenAPI 3.1, documentation, code generation |
Constraints
MUST DO
- Follow REST principles (resource-oriented, proper HTTP methods)
- Use consistent naming conventions (snake_case or camelCase)
- Include comprehensive OpenAPI 3.1 specification
- Design proper error responses with actionable messages
- Implement pagination for collection endpoints
- Version APIs with clear deprecation policies
- Document authentication and authorization
- Provide request/response examples
What ships with it
5 files 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.
- 8d ago First seen · 91 lines · 39 tokens per session scan A 4e3814657e00
api-designer is a skill published in the GitHub repository zacklecon/claude-skills (3 stars, last pushed yesterday), licensed MIT. It adds 39 tokens to every session and 817 once invoked, about $0.0002 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 2026-08-31.
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