error-code-guide

A guide to creating consistent error codes in the PREFIXCATEGORYNUMBER format and designing API error handling. An API is a defined way for software systems to communicate.

In plain words
What is it for?
Use it when defining error codes, designing error handling, or planning errors for an API.
Why use it?
It helps applications return errors in a predictable format that other software and developers can handle consistently.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/asiaostrich/universal-dev-standards/error-code-guide
Any agent
npx skills add AsiaOstrich/universal-dev-standards --skill error-code-guide
Clone the repo
git clone --depth 1 https://github.com/AsiaOstrich/universal-dev-standards

Made for: Claude Code, Codex.

Per session 116 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,474 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00116 $0.02474
Opus 5 $0.00058 $0.01237
Sonnet 5 $0.00023 $0.00495
Haiku 4.5 $0.00012 $0.00247

Measured 2d ago against content hash 8cee657599c4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

error-code-guide 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 2d 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.

.claude/skills/error-code-guide/SKILL.md · 305 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Changes

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.

  1. 2d ago First seen · 305 lines · 116 tokens per session scan A 8cee657599c4

Subscribe to this mod's changes

error-code-guide is a skill published in the GitHub repository AsiaOstrich/universal-dev-standards (72 stars, last pushed 4d ago), with no licence file. It adds 116 tokens to every session and 2,474 once invoked, about $0.0006 per session on Opus 5. 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.

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