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/jukrap/ai-agent-playbook/request-validation-error-contractnpx skills add jukrap/ai-agent-playbook --skill request-validation-error-contractgit clone --depth 1 https://github.com/jukrap/ai-agent-playbookWrote 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/jukrap/ai-agent-playbook/request-validation-error-contract)<a href="https://agentmods.dev/skills/jukrap/ai-agent-playbook/request-validation-error-contract"><img src="https://agentmods.dev/badge/skills/jukrap/ai-agent-playbook/request-validation-error-contract.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00026 | $0.00223 |
| Opus 5 | $0.00013 | $0.00112 |
| Sonnet 5 | $0.00005 | $0.00045 |
| Haiku 4.5 | $0.00003 | $0.00022 |
Grade A, and why
request-validation-error-contract 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.
What it actually says
Request Validation Error Contract
Protect request and failure contracts before changing backend validation or error handling.
Workflow
- Identify route, handler, schema, DTO, middleware, exception mapper, client callers, and documented error shape.
- Separate parsing, validation, authorization, business rule failure, conflict, rate limit, and unexpected error paths.
- Preserve stable status codes, error codes, field paths, localization keys, and retry semantics unless the change is explicitly versioned.
- Keep sensitive values out of error bodies, logs, traces, and validation messages.
- Verify success, invalid input, missing permission, conflict, not found, and unexpected failure paths.
- Pair with
api-contract-boundarywhen frontend mocks, generated clients, OpenAPI, or external consumers depend on the shape.
Reference
Read references/request-error-contract.md before editing validators, DTOs, exception filters, middleware, or error response schemas.
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 · 22 lines · 26 tokens per session scan A 491e06e30682
request-validation-error-contract is a skill published in the GitHub repository jukrap/ai-agent-playbook (2 stars, last pushed 20d ago), licensed MIT. It adds 26 tokens to every session and 223 once invoked, about $0.0001 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 2026-08-31.
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