# Middleware Skill > describe how to write middleware code in the codebase, use when you need a filter or interceptor to process the request or response Use when this capability is needed. - Skill: `tomevault-io/middleware-skill` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/middleware-skill` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/middleware-skill/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/middleware-skill --- # middleware best practices the document outlines the best practices for writing middleware code in the codebase. ## when to use this skill when you need a filter or interceptor to process the request or response ## best practices + when you have multiple data to process, you should write separate middleware to process each data + if you need to check data present or not, try to use cache instead of database query + you should fail fast if the request is invalid, don't process the request further + you should return 400 bad request if request is invalid --- > Source: [ambersun1234/skills](https://github.com/ambersun1234/skills) — distributed by [TomeVault](https://tomevault.io).