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 agentmods add skills/cass-2003/local-workflow-skill/api-error-observabilitynpx skills add cass-2003/local-workflow-skill --skill api-error-observabilitygit clone --depth 1 https://github.com/cass-2003/local-workflow-skillWhat 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 | $0.00094 | $0.00786 |
| Opus 5 | $0.00047 | $0.00393 |
| Sonnet 5 | $0.00019 | $0.00157 |
| Haiku 4.5 | $0.00009 | $0.00079 |
Grade A, and why
api-error-observability 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 3d 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.
How it starts
The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Error And Observability
Core Goal
Make failures understandable to users, clients, operators, and future agents. Every important error should answer: what happened, who is affected, can it be retried, and where is the evidence?
Error Contract
Use a stable error shape:
{
"type": "https://docs.example.com/errors/quota-exceeded",
"code": "quota_exceeded",
"message": "Quota exceeded for this workspace.",
"request_id": "req_123",
"retryable": false,
"details": {
"limit": 1000,
"window": "month"
}
}
Expose safe messages to clients. Put sensitive internals only in logs.
HTTP Status Guidance
| Status | Use For |
|---|---|
| 400 | invalid request shape |
| 401 | not authenticated |
| 403 | authenticated but not allowed |
| 404 | not found or intentionally hidden |
| 409 | conflict, version mismatch, duplicate invariant |
| 422 | semantic validation failure |
| 429 | rate limited |
| 500 | unhandled server error |
| 503 | temporary service unavailable |
Do not return 200 with an error object for normal APIs.
Logging Rules
- Log structured fields, not only prose.
- Include request id, trace id, user id if safe, tenant id if safe, route, method, status, duration, and error code.
- Redact secrets and PII.
- Log at boundaries: request start/end, external calls, queue jobs, auth failures, and critical domain transitions.
- Avoid logging full request bodies by default.
Trace And Metrics
Minimum metrics:
- request count by route/status
- latency histogram by route
- error count by code
- dependency latency and failure rate
- queue lag if API enqueues work
Minimum tracing:
- inbound request span
- database query spans or summarized DB timing
- external HTTP calls
- queue publish/consume spans
- cache calls when they affect latency
SLO And Alerting
Alert on symptoms before causes:
- p95/p99 latency above SLO
- error rate above threshold
- dependency failure spike
- queue lag above threshold
- no traffic when traffic is expected
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.
- 3d ago First seen · 117 lines · 94 tokens per session scan A fa6425f08358
api-error-observability is a skill published in the GitHub repository cass-2003/local-workflow-skill (12 stars, last pushed 1mo ago), licensed MIT. It adds 94 tokens to every session and 786 once invoked, about $0.0005 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.
Other skills, from other repositories
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
brainstorming
You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.
auto-perf-optimize
Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.
chat-perf
Run chat perf benchmarks and memory leak checks against the local dev build or any published VS Code version. Use when investigating chat rendering regressions, validating perf-sensitive changes to chat UI, or checking for memory leaks in the chat response pipeline.
chat-pet-sprite-creation
Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.
cpu-profile-analysis
Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…