# API Design > Design API endpoints, schemas, and contracts. Use when defining public interfaces or data models. Use when this capability is needed. - Skill: `tomevault-io/api-design-18` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/api-design-18` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/api-design-18/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Integrations & APIs - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/api-design-18 --- # API Design Define the interface contracts for APIs, including endpoints, request/response schemas, and error handling. ## Process 1. Review spec.md and architecture.md 2. Define endpoints and HTTP methods 3. Design request and response schemas 4. Define error responses and codes 5. Consider versioning strategy ## Output Create `api-design.md` using the template in `templates/api-design.md`. ## Tips - Use consistent naming conventions - Design for backwards compatibility - Include example payloads - Document rate limits if applicable - Consider pagination for list endpoints --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/amattas) — claim your Tome and manage your conversions.