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 jabrena/plinth --skill 303-frameworks-spring-boot-validationgit clone --depth 1 https://github.com/jabrena/plinthWrote 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/jabrena/plinth/303-frameworks-spring-boot-validation)<a href="https://agentmods.dev/skills/jabrena/plinth/303-frameworks-spring-boot-validation"><img src="https://agentmods.dev/badge/skills/jabrena/plinth/303-frameworks-spring-boot-validation.svg" alt="Measured on agentmods" 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 | $0.00113 | $0.00555 |
| Opus 5 | $0.00056 | $0.00278 |
| Sonnet 5 | $0.00023 | $0.00111 |
| Haiku 4.5 | $0.00011 | $0.00056 |
Grade A, and why
303-frameworks-spring-boot-validation 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 5d 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 — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Spring Boot Validation Guidelines
Apply Spring Boot validation best practices at API boundaries.
What is covered in this Skill?
- Bean Validation annotations on DTOs and command models
- @Valid / @Validated on controllers and method parameters
- Validation groups for create/update workflows
- Custom constraint annotations and validators
- Consistent 400 error responses for validation failures
Scope: Apply recommendations based on the reference rules and good/bad examples.
Constraints
Before applying validation changes, ensure the project compiles. After improvements, run full verification.
- MANDATORY: Run
./mvnw compileormvn compilebefore applying any change - SAFETY: If compilation fails, stop immediately
- VERIFY: Run
./mvnw clean verifyormvn clean verifyafter applying improvements - BEFORE APPLYING: Read the reference for detailed rules and examples
When to use this skill
- Add validation support in Spring Boot
- Review Spring Boot validation rules
- Improve request validation in Spring Boot REST APIs
- Add custom Bean Validation constraints in Spring Boot
- Validate configuration properties in Spring Boot
- Improve nested DTO validation in Spring Boot
Workflow
- Read reference and assess project context
Read references/303-frameworks-spring-boot-validation.md and inspect the current project setup before proposing changes.
- Gather scope and decide target improvements
Identify requested outcomes, constraints, and the minimum safe set of changes to apply.
- Apply framework-aligned changes
Implement or refactor validation-related configuration/code following the reference patterns and project conventions.
- Run verification and report results
Execute appropriate build/tests and summarize what changed, what was verified, and any follow-up actions.
Reference
For detailed guidance, examples, and constraints, see references/303-frameworks-spring-boot-validation.md.
What ships with it
1 file 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.
- 5d ago First seen · 62 lines · 113 tokens per session scan A a07e14b8ff6d
303-frameworks-spring-boot-validation is a skill published in the GitHub repository jabrena/plinth (437 stars, last pushed today), licensed Apache-2.0. It adds 113 tokens to every session and 555 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 2026-09-03.
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