API Skills
A curated collection of 10 api skills for building with AI coding agents.
CORS Configurator
Diagnose and fix a failing cross-origin browser request — read the exact console error, work out whether it's a simple or preflighted request, and set the minimal correct Access-Control-* response headers (including the wildcard-with-credentials trap and the OPTIONS preflight) on the server. Use when the browser blocks a fetch/XHR with a CORS error but the API itself works from curl or Postman.
GraphQL Schema Designer
Design a clean, evolvable GraphQL schema (SDL) that won't paint you into a corner — model the graph around domain types and their relationships rather than as RPC-over-GraphQL, set nullability deliberately, standardize lists with Relay connections, plan DataLoader batching for per-parent fields, and evolve by adding + @deprecated instead of versioning. Use when designing a new GraphQL API, reviewing an SDL, or migrating REST endpoints to a graph.
Idempotency Designer
Make unsafe, retryable API operations idempotent so a client retry or a network hiccup can't double-charge, double-create, or double-send — design a client-supplied idempotency key, an atomic store-and-check (unique constraint or conditional write), in-flight conflict handling, and a retention policy. Use when a POST/mutation can be retried (payments, order creation, sends, webhooks), or when duplicate side effects have already shown up in production.
LLM Output Schema Generator
Turn an example of the data you want from an LLM into a precise, validated output schema (Pydantic / Zod / JSON Schema) and wire it into structured-output calls. Use when adding typed LLM output, replacing brittle JSON parsing, or designing an extraction shape.
MCP Server Scaffolder
Scaffold a new Model Context Protocol (MCP) server from a description — pick the SDK and transport, generate a typed first tool with a strict schema, and wire up MCP Inspector testing and the client-registration command. Use when starting a new MCP server and you want a correct, runnable skeleton instead of copying a README.
Pagination Designer
Design correct, scalable pagination (plus the filtering and sorting that ride with it) for a list endpoint — pick cursor (keyset) vs offset and justify it, define an opaque cursor with a unique tiebreaker so no row is skipped or repeated, return a consistent envelope, bound page size, and name the indexes the sort actually needs. Use when adding a list endpoint, when OFFSET pagination crawls on a large table, or when clients see duplicate or missing rows while paging.
Provider Fallback Wrapper
Wrap LLM calls so a provider outage, rate limit, or timeout degrades gracefully — with multi-provider fallback, bounded retries with backoff, and timeouts. Use when an app depends on a single model/provider and needs production resilience.
Rate Limiter Designer
Design and implement API rate limiting that actually holds under load — pick the algorithm (token bucket vs sliding-window-counter vs fixed window) and justify it, choose the limiting key and per-tier limits, use cross-instance atomic storage, and return standard 429 signals. Use when protecting an API from abuse or scrapers, enforcing per-tier quotas, or replacing an in-memory limiter that breaks behind multiple replicas.
Tool Definition Generator
Generate clean function/tool schemas for an LLM agent from existing code or a spec — accurate JSON Schema, model-facing descriptions, honest required fields, and enums that make invalid calls impossible. Use when wiring functions into an agent's tool-calling loop.
Webhook Handler Scaffolder
Scaffold a robust inbound webhook handler that verifies the signature on the raw body first, dedupes on the provider's event id, acknowledges fast, and processes asynchronously — the four things naive handlers get wrong. Use when wiring up events from a third party (Stripe, GitHub, Shopify, Slack, Twilio), when a provider keeps retrying because your endpoint times out or 500s, or when duplicate events are double-charging or double-creating records.