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 oborchers/fractional-cto --skill errors-and-status-codesgit clone --depth 1 https://github.com/oborchers/fractional-ctoWrote 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/oborchers/fractional-cto/errors-and-status-codes)<a href="https://agentmods.dev/skills/oborchers/fractional-cto/errors-and-status-codes"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/errors-and-status-codes.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 7 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Data Exfiltration · line 76 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 95 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 222 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 228 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 248 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 257 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 275 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
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 | $0.00080 | $0.03292 |
| Opus 5 | $0.00040 | $0.01646 |
| Sonnet 5 | $0.00016 | $0.00658 |
| Haiku 4.5 | $0.00008 | $0.00329 |
Grade A, and why
errors-and-status-codes 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 8d 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 — 306 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Errors Are Part of Your API's Interface
A well-designed error response teaches the developer what went wrong, points them to the fix, and gives their code enough information to handle it automatically. Bad errors generate support tickets. Good errors eliminate them.
The HTTP status code is the first thing a client reads. It must be accurate, specific, and machine-actionable. The status code conveys the category of outcome; the response body conveys the detail. Never return 200 with { "success": false } -- it breaks HTTP semantics, defeats monitoring, and confuses every layer of infrastructure between your server and the client.
Status Code Decision Table
Pick the most specific code that applies. When in doubt, move down the table.
2xx -- Success
| Code | When to Use |
|---|---|
| 200 OK | GET, PUT, PATCH, and POST actions that are not resource creation. Return the resource. |
| 201 Created | A new resource was created. Return the resource and a Location header with its URI. |
| 202 Accepted | Async work was queued but not yet complete. Return a status object with a job URL. |
| 204 No Content | Success with intentionally no body. Use for DELETE. Also valid for PUT/PATCH when you omit the updated resource. |
3xx -- Redirects
| Code | When to Use |
|---|---|
| 301 Moved Permanently | Resource has a new canonical URI. Clients should update bookmarks. |
| 304 Not Modified | Resource unchanged since If-None-Match or If-Modified-Since. Critical for caching. |
| 307 Temporary Redirect | Temporary reroute, method and body preserved. |
4xx -- Client Errors
| Code | When to Use |
|---|---|
| 400 Bad Request | Malformed request. Unparseable JSON, missing required top-level fields, wrong content type. The problem is syntactic. |
| 401 Unauthorized | Authentication failed or missing. "Who are you?" |
| 403 Forbidden | Authenticated but not authorized. "I know who you are, and you cannot do this." |
| 404 Not Found | Resource does not exist. Also use 404 instead of 403 to hide resource existence from unauthorized callers. |
| 405 Method Not Allowed | HTTP method not supported. Include an Allow header listing valid methods. |
| 409 Conflict | State conflict -- duplicate resource, concurrent modification, invalid state transition. |
| 422 Unprocessable Content | Syntactically valid but semantically invalid. Business rule violations, field-level validation failures. |
| 429 Too Many Requests | Rate limit exceeded. Must include Retry-After header. |
What ships with it
2 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.
- 8d ago First seen · 306 lines · 80 tokens per session scan A 08ee6c6698e1
errors-and-status-codes is a skill published in the GitHub repository oborchers/fractional-cto (29 stars, last pushed 1mo ago), licensed MIT. It adds 80 tokens to every session and 3,292 once invoked, about $0.0004 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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