Borrowing it
Nothing to install: this file belongs to extra-org/extra. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/extra-org/extra/main/.claude/skills/yaml-schema/SKILL.mdgit clone --depth 1 https://github.com/extra-org/extraWrote 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/extra-org/extra/yaml-schema)<a href="https://agentmods.dev/skills/extra-org/extra/yaml-schema"><img src="https://agentmods.dev/badge/skills/extra-org/extra/yaml-schema/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/extra-org/extra/yaml-schema"><img src="https://agentmods.dev/badge/skills/extra-org/extra/yaml-schema.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00036 | $0.00511 |
| Opus 5.5 | $0.00014 | $0.00204 |
| Sonnet 5.5 | $0.00007 | $0.00102 |
| Haiku 4.5 | $0.00004 | $0.00051 |
Grade A, and why
yaml-schema 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 2mo 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
Skill: YAML Schema & Validation
When to use this skill
Use this when working on loading YAML configs, defining schema models, or
validating the Agent Engine specification. Primary task:
tasks/0002-yaml-schema-and-validation.md.
Files to read first
AGENTS.mddocs/YAML_SPEC.mdexamples/agents.ymlexamples/config.schema.jsondocs/adr/0002-yaml-is-compiled-not-executed-directly.md
Architecture rules
- YAML is declarative data, never code.
- The spec has two halves: flat declarations and
graphtopology. - Validation must happen before compilation.
- Runtime layers consume only validated/compiled models, never raw YAML dicts.
- Secrets are never values in YAML.
Implementation rules
- Define typed schema models in
src/agentplatform/spec. - Validation belongs in
src/agentplatform/validation. - Report all validation errors with useful locations.
- Enforce: required
systemandgraph; one graph root; graph ids exist inorchestratorsoragents; no cycles; referenced resolvers/tools/MCPs exist; orchestrators haveprompts.orchestrator; model overrides are complete; protected nodes require the access plugin at startup. - Keep schema/validation separate from the compiler.
Validation checklist
- Schema models cover
docs/YAML_SPEC.md. -
examples/agents.ymlvalidates successfully. - Dangling references, missing/multiple roots, and cycles fail clearly.
- Unknown keys and hardcoded secrets are rejected.
- Tests cover valid and invalid specs.
-
make checkpasses.
Common mistakes to avoid
- Mixing validation with compilation or runtime logic.
- Failing fast on the first error instead of collecting all errors.
- Reintroducing the old
definitions/hierarchyshape. - Letting unknown/typo'd keys pass silently.
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.
- 2mo ago First seen · 64 lines · 36 tokens per session scan A 6e52ec1c86fb
yaml-schema is a skill published in the GitHub repository extra-org/extra (117 stars, last pushed 5d ago), licensed MIT. It adds 36 tokens to every session and 511 once invoked, about $0.0001 per session on Opus 5.5. 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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