# api-error-handling

This skill structures API error handling around shared responses, validation, logs, retries, and monitoring. Use it while debugging failures or adding recovery paths.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 508 installs · ★ 371
- Author: aj-geddes
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/aj-geddes/useful-ai-prompts/tree/HEAD/skills/api-error-handling/SKILL.md
- Updated: 2026-03-04
- HTML: https://affpapa.org/en/nevibecode/skills/api-error-handling

## What it does

api-error-handling gives an API a shared error model across endpoints. It covers typed errors, HTTP status handling, request and trace IDs, client-facing messages, logging, and error-rate tracking. Input checks happen before the main request work.

Its `references/` directory contains guides for the `ERROR_CODES` map and response formatting in Node.js and Python, exponential backoff, circuit breakers, Sentry integration, error metrics, the `/metrics/errors` endpoint, and validation guards. A Node.js `ApiError` class is included.

The guidance rules out retries for non-idempotent operations and 4xx responses. It also separates log levels for server and client errors, while sensitive data such as tokens and passwords must stay out of logs.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add aj-geddes/useful-ai-prompts --skill api-error-handling -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/api-error-handling/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/api-error-handling/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add aj-geddes/useful-ai-prompts --skill api-error-handling -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/api-error-handling/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add aj-geddes/useful-ai-prompts --skill api-error-handling -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/api-error-handling/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install aj-geddes/useful-ai-prompts api-error-handling
```

2. **Manually: put the files in place**
- File: `.github/skills/api-error-handling/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add aj-geddes/useful-ai-prompts --skill api-error-handling -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/aj-geddes/useful-ai-prompts --path skills/api-error-handling
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/api-error-handling/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add aj-geddes/useful-ai-prompts --skill api-error-handling -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/aj-geddes/useful-ai-prompts/tree/HEAD/skills/api-error-handling/SKILL.md

## When to use it
- standardize error responses across API endpoints
- attach `requestId` and trace data to failures
- add exponential-backoff retries for transient errors
- validate request data before processing
- track error spikes with metrics and alerts

## Example prompts
- Apply one error response shape to every endpoint and add `requestId`.
- Set up exponential backoff and a circuit breaker for transient API failures.
- Review this Node.js API’s input validation and error middleware.

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 48a7dbb7a6889ecf.

BEGIN THIRD-PARTY FILE 48a7dbb7a6889ecf
````text
---
name: api-error-handling
description: >
  Implement comprehensive API error handling with standardized error responses,
  logging, monitoring, retry logic, and validation patterns. Use when building
  resilient APIs, debugging issues, improving error reporting, implementing
  retry logic, handling HTTP error codes, managing API timeouts, designing
  error response handling, or adding circuit breaker patterns.
---

# API Error Handling

## Table of Contents

- [Overview](#overview)
- [When to Use](#when-to-use)
- [Quick Start](#quick-start)
- [Reference Guides](#reference-guides)
- [Best Practices](#best-practices)

## Overview

Build robust error handling systems with standardized error responses, detailed
logging, error categorization, and user-friendly error messages. This skill
covers the full lifecycle from throwing typed errors through logging, monitoring,
and client-facing response formatting.

## When to Use

- Handling API errors consistently across endpoints
- Debugging production issues with request tracing
- Implementing error recovery strategies (retry, circuit breaker)
- Monitoring and alerting on error rates
- Providing meaningful, actionable error messages to clients
- Validating request inputs before processing
- Tracking error patterns over time

## Quick Start

Minimal standardized error response format:

```json
{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Input validation failed",
    "statusCode": 422,
    "requestId": "req_abc123xyz789",
    "timestamp": "2025-01-15T10:30:00Z",
    "details": [
      { "field": "email", "message": "Invalid email format", "code": "INVALID_EMAIL" }
    ]
  }
}
```

Custom error class (Node.js):

```javascript
class ApiError extends Error {
  constructor(code, message, statusCode = null, details = null) {
    super(message);
    this.code = code;
    this.statusCode = statusCode || ERROR_CODES[code]?.status || 500;
    this.details = details;
    this.timestamp = new Date().toISOString();
  }
}

// Usage
throw new ApiError("NOT_FOUND", "User not found", 404);
throw new ApiError("VALIDATION_ERROR", "Missing fields", 422, fieldErrors);
```

## Reference Guides

Detailed implementations in the `references/` directory:

| Guide | Contents |
|---|---|
| [Error Codes & Response Format](references/error-codes-reference.md) | Complete `ERROR_CODES` map, response formatter, global middleware (Node.js + Python) |
| [Retry Strategies & Circuit Breaker](references/retry-strategies.md) | Exponential backoff, jitter, circuit breaker pattern |
| [Monitoring & Tracking](references/monitoring-patterns.md) | Sentry integration, error rate metrics, `/metrics/errors` endpoint |
| [Validation Patterns](references/validation-examples.md) | Input validation, schema guards, detecting bad responses before errors occur |

## Best Practices

### ✅ DO
````
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