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 stefan-jansen/claude-code-toolkit --skill api-authenticationgit clone --depth 1 https://github.com/stefan-jansen/claude-code-toolkitWrote 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/stefan-jansen/claude-code-toolkit/api-authentication)<a href="https://agentmods.dev/skills/stefan-jansen/claude-code-toolkit/api-authentication"><img src="https://agentmods.dev/badge/skills/stefan-jansen/claude-code-toolkit/api-authentication/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/stefan-jansen/claude-code-toolkit/api-authentication"><img src="https://agentmods.dev/badge/skills/stefan-jansen/claude-code-toolkit/api-authentication.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 7 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Privilege Escalation · line 122 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 186 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 264 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 202 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 265 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 271 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 640 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
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 | $0.00077 | $0.05510 |
| Opus 5.5 | $0.00031 | $0.02204 |
| Sonnet 5.5 | $0.00015 | $0.01102 |
| Haiku 4.5 | $0.00008 | $0.00551 |
Grade A, and why
api-authentication 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 1mo 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 — 806 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Authentication Patterns
Comprehensive guide to implementing secure API authentication including JWT, OAuth 2.0, API keys, and session-based patterns. Covers when to use each approach, security best practices, and common vulnerabilities to avoid.
Quick Reference
When to use this skill:
- Implementing API authentication
- Choosing between auth strategies (JWT vs OAuth vs sessions)
- Securing API endpoints
- Implementing token refresh logic
- Debugging authentication issues
- Preventing auth vulnerabilities
Common triggers:
- "How should I implement authentication"
- "JWT vs OAuth vs API keys"
- "How to secure this API"
- "Implement refresh tokens"
- "Store authentication tokens securely"
- "Fix authentication vulnerability"
Prevents vulnerabilities:
- Token theft and replay attacks
- Insecure token storage
- Missing token expiration
- Weak password hashing
- CSRF attacks
Part 1: Authentication Strategy Decision Matrix
When to Use Each Pattern
| Pattern | Best For | Pros | Cons |
|---|---|---|---|
| JWT | Stateless APIs, microservices, mobile apps | Stateless, scalable, works across domains | Tokens can't be revoked easily, larger payload |
| OAuth 2.0 | Third-party access, social login, delegation | Industry standard, fine-grained permissions | Complex to implement, requires authorization server |
| API Keys | Server-to-server, public APIs, rate limiting | Simple, great for service accounts | Not for users, can't be scoped easily |
| Sessions | Traditional web apps, SSR, same-domain | Revocable, server-controlled, secure | Requires server state, doesn't scale horizontally easily |
Decision Tree
START: What type of client?
├─ Mobile app or SPA?
│ └─ Use JWT (stateless, works across domains)
│
├─ Third-party integration?
│ └─ Use OAuth 2.0 (delegation, scoped permissions)
│
├─ Service-to-service?
│ └─ Use API Keys (simple, rate-limitable)
│
└─ Traditional web app (same domain)?
└─ Use Sessions (revocable, server-controlled)
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.
- 1mo ago First seen · 806 lines · 77 tokens per session scan A 7dadce4c7c49
api-authentication is a skill published in the GitHub repository stefan-jansen/claude-code-toolkit (89 stars, last pushed 3mo ago), licensed MIT. It adds 77 tokens to every session and 5,510 once invoked, about $0.0003 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.
Other skills, from other repositories
sglang
Fast structured generation and serving for LLMs with RadixAttention prefix caching. Use for JSON/regex outputs, constrained decoding, agentic workflows with tool calls, or when you need 5× faster inference than vLLM with prefix sharing. Powers 300,000+ GPUs at xAI, AMD, NVIDIA, and LinkedIn.
amazon-location-service
Integrates Amazon Location Service APIs for AWS applications. Use this skill when users want to add maps (interactive MapLibre or static images); geocode addresses to coordinates or reverse geocode coordinates to addresses; calculate routes, travel times, or service areas; find places and businesses through text…
amplify-workflow
Build and deploy full-stack web and mobile apps with AWS Amplify Gen2 (TypeScript code-first). Covers auth (Cognito), data (AppSync/DynamoDB including schema modeling, enum types, relationships, authorization rules), storage (S3), functions, APIs, and AI (Amplify AI Kit with Bedrock). Supports React, Next.js, Vue…
aws-lambda-durable-functions
Build resilient, long-running, multi-step applications with AWS Lambda durable functions with automatic state persistence, retry logic, and orchestration for long-running executions. Covers the critical replay model, step operations, wait/callback patterns, error handling with saga pattern, testing with…
api-gateway
Build, manage, and operate APIs with Amazon API Gateway (REST, HTTP, and WebSocket). Triggers on phrases like: API Gateway, REST API, HTTP API, WebSocket API, custom domain, Lambda authorizer, usage plan, throttling, CORS, VPC link, private API. Also covers troubleshooting API Gateway errors (4xx, 5xx, timeout, CORS…
aws-lambda
Design, build, deploy, test, and debug serverless applications with AWS Lambda. Triggers on phrases like: Lambda function, event source, serverless application, API Gateway, EventBridge, Step Functions, serverless API, event-driven architecture, Lambda trigger. For deploying non-serverless apps to AWS, use…