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.
npx skills add HoangNguyen0403/agent-skills-standard --skill common-error-handlinggit clone --depth 1 https://github.com/HoangNguyen0403/agent-skills-standardWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/common-error-handling)<a href="https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/common-error-handling"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/common-error-handling/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/hoangnguyen0403/agent-skills-standard/common-error-handling"><img src="https://agentmods.dev/badge/skills/hoangnguyen0403/agent-skills-standard/common-error-handling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00055 | $0.00467 |
| Opus 5 | $0.00028 | $0.00234 |
| Sonnet 5 | $0.00011 | $0.00093 |
| Haiku 4.5 | $0.00006 | $0.00047 |
Grade A, and why
common-error-handling 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 9d 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.
What it actually says
Error Handling Standards
Priority: P1 (HIGH)
Error Architecture
- API Layer: Map domain errors to HTTP responses globally.
- Domain Layer: Throw pure business errors. NO HTTP status codes here.
- Infra Layer: Wrap 3rd-party exceptions. NOT leak raw DB errors to API.
- Standard Shape: APIs must return standardized JSON envelope:
See implementation examples for standard error response shape.
Error Mechanics
- Wrap: Add context (
fmt.Errorf("process: %w", err),new Error('msg', { cause })). - Replace: Only when original error leaks sensitive details.
- Error Codes: Use
SCREAMING_SNAKE_CASEIDs (ORDER_PAYMENT_FAILED).
Anti-Patterns
- Swallowing Errors: Never
catch(e) {}without logging or re-throwing. - Never silently ignore an error: an empty catch must become an explicit log, handling branch, returned error, or rethrow.
- Stack Traces: Never expose stack traces in API responses.
- Generic 500s: Use
400with specific details for validation instead of 500.
References
Failure-handling checklist
- Never swallow errors: do not use an empty
catchor silently ignore a failure. Log, wrap, rethrow, or map it deliberately at the correct boundary.
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 9d ago First seen · 55 lines · 55 tokens per session scan A 0e38dbe7c85e
common-error-handling is a skill published in the GitHub repository HoangNguyen0403/agent-skills-standard (565 stars, last pushed 3d ago), licensed MIT. It adds 55 tokens to every session and 467 once invoked, about $0.0003 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 2026-09-03.
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