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 rrezartprebreza/spring-boot-skills --skill problem-details-rfc9457git clone --depth 1 https://github.com/rrezartprebreza/spring-boot-skillsWrote 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/rrezartprebreza/spring-boot-skills/problem-details-rfc9457)<a href="https://agentmods.dev/skills/rrezartprebreza/spring-boot-skills/problem-details-rfc9457"><img src="https://agentmods.dev/badge/skills/rrezartprebreza/spring-boot-skills/problem-details-rfc9457/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/rrezartprebreza/spring-boot-skills/problem-details-rfc9457"><img src="https://agentmods.dev/badge/skills/rrezartprebreza/spring-boot-skills/problem-details-rfc9457.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 5 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 25 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 44 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 55 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 70 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 83 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 | $0.00036 | $0.00794 |
| Opus 5 | $0.00018 | $0.00397 |
| Sonnet 5 | $0.00007 | $0.00159 |
| Haiku 4.5 | $0.00004 | $0.00079 |
Grade A, and why
problem-details-rfc9457 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 — 87 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Problem Details - RFC 9457
Choose the error contract
Inspect existing advice, security entry points and API tests first. Keep one error policy per API. Success DTOs or success envelopes can coexist with Problem Details errors: RFC 9457 specifies errors, not success representations.
For an API using Problem Details, enable Spring's built-in MVC exception handling:
spring:
mvc:
problemdetails:
enabled: true
For WebFlux use spring.webflux.problemdetails.enabled and reactive exception handling;
the servlet templates below are not WebFlux handlers.
Domain errors
Use the compiled DomainException together with ProblemDetailExceptionHandler. The handler maps all subclasses using their declared status and stable error code:
- OrderNotFoundException: 404.
- InsufficientInventoryException: 422.
- BusinessRuleViolationException: 422.
Each public class has its own file. These are API-facing exceptions with HTTP status metadata; for a framework-free domain, keep domain exceptions independent and map them in the web adapter. Do not expose arbitrary persistence or infrastructure exception messages.
The advice extends ResponseEntityExceptionHandler to preserve Spring's handling of framework
exceptions. Validation returns 400 with field violations; unexpected failures return a generic
500 while retaining the full exception only in server logs. Keep nullable validation messages safe.
Filter-level authentication failures need an AuthenticationEntryPoint; authorization failures
need an AccessDeniedHandler. Controller advice does not cover the security filter chain.
Response fields
{
"type": "https://api.example.com/errors/order_not_found",
"title": "Not Found",
"status": 404,
"detail": "Order not found",
"instance": "/api/orders/123",
"errorCode": "ORDER_NOT_FOUND"
}
What ships with it
8 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.
- agents/openai.yaml 211 B
- examples/bad-exception-handler.java 1.6 KB
- examples/good-exception-handler.java 2.3 KB
- templates/BusinessRuleViolationException.java 358 B
- templates/DomainException.java 622 B
- templates/InsufficientInventoryException.java 513 B
- templates/OrderNotFoundException.java 366 B
- templates/ProblemDetailExceptionHandler.java 3.8 KB
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 Changed · -61 lines · -7 tokens per session 6b4e84ff6fd6
- 12d ago First seen · 148 lines · 43 tokens per session scan A 9c57c661212f
problem-details-rfc9457 is a skill published in the GitHub repository rrezartprebreza/spring-boot-skills (261 stars, last pushed 4d ago), licensed MIT. It adds 36 tokens to every session and 794 once invoked, about $0.0002 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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