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/JoasASantos/ClaudeAdvancedPluginsWrote 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/commands/joasasantos/claudeadvancedplugins/backend-api-design)<a href="https://agentmods.dev/commands/joasasantos/claudeadvancedplugins/backend-api-design"><img src="https://agentmods.dev/badge/commands/joasasantos/claudeadvancedplugins/backend-api-design/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/commands/joasasantos/claudeadvancedplugins/backend-api-design"><img src="https://agentmods.dev/badge/commands/joasasantos/claudeadvancedplugins/backend-api-design.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 | $0.00000 | $0.00273 |
| Opus 5.5 | $0.00000 | $0.00109 |
| Sonnet 5.5 | $0.00000 | $0.00055 |
| Haiku 4.5 | $0.00000 | $0.00027 |
Grade A, and why
backend-api-design 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.
What it actually says
Backend API Design Specialist
You are an API design expert. Given a feature or domain, produce a complete API specification.
Process
- Domain Analysis — Identify resources, relationships, and operations
- Endpoint Design — RESTful routes with proper HTTP semantics
- Schema Definition — Request/response bodies with validation rules
- Auth & Permissions — Authentication method and RBAC/ABAC policies
- Error Handling — Standardized error codes and messages
- Versioning Strategy — URL path, header, or query param versioning
- Documentation — OpenAPI 3.1 spec snippet
Output
Produce an OpenAPI-compatible specification with:
- Path definitions with all CRUD operations
- Request/response schemas using JSON Schema
- Authentication requirements per endpoint
- Rate limiting headers
- Pagination strategy (cursor-based preferred)
- HATEOAS links where beneficial
- Example requests and responses
Rules
- Use plural nouns for resource names
- Nest resources max 2 levels deep
- Use 201 for creation, 204 for deletion
- Include ETag headers for caching
- Use RFC 7807 Problem Details for errors
- Always include correlation/request IDs
- Design for backward compatibility
Apply to: $ARGUMENTS
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 · 36 lines · 0 tokens per session scan A 2c7542cef3ce
backend-api-design is a command published in the GitHub repository JoasASantos/ClaudeAdvancedPlugins (157 stars, last pushed 7mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 273 tokens. 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 commands, from other repositories
init
Initialize configurations for Supabase local development.
http-service
Build, review or debug a Bun HTTP service. Loads the http-service skill, then works the task through its workflow.
api-contract-review
Review an API contract (shapes, errors, auth model) BEFORE implementation for naming, versioning, pagination, idempotency, and fit with existing endpoints. Use when designing or changing endpoints. Do not use when the API is already implemented (use review-hard or repo-consistency-sweep).
start-10-1
A guided lesson on setting up clasp, a command-line tool for managing Google Apps Script projects, and connecting it to Google’s Apps Script API.
build
Discover an AI Gateway's models and MCP tools, retrieve a credential, and integrate them into your app — call a model, connect MCP tools, or scaffold a runnable agent.
fastapi
FastAPI application design and implementation conventions. Use this skill when building, updating, or reviewing FastAPI services, routers, dependencies, request/response schemas, streaming endpoints, or API tests. Trigger on FastAPI-specific work such as path operation design, dependency injection, response models…