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 JayRHa/AgentSkills --skill json-schema-authorgit clone --depth 1 https://github.com/JayRHa/AgentSkillsWrote 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/jayrha/agentskills/json-schema-author)<a href="https://agentmods.dev/skills/jayrha/agentskills/json-schema-author"><img src="https://agentmods.dev/badge/skills/jayrha/agentskills/json-schema-author/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/jayrha/agentskills/json-schema-author"><img src="https://agentmods.dev/badge/skills/jayrha/agentskills/json-schema-author.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00100 | $0.02088 |
| Opus 5.5 | $0.00040 | $0.00835 |
| Sonnet 5.5 | $0.00020 | $0.00418 |
| Haiku 4.5 | $0.00010 | $0.00209 |
Grade A, and why
json-schema-author 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 1mo 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 — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.
JSON Schema Author
Overview
Keywords: JSON Schema, Draft 2020-12, Draft-07, $schema, $ref, $defs, validation, config schema, API schema, OpenAPI, additionalProperties, oneOf, anyOf, allOf, if/then/else, format, pattern, const, enum, error messages, ajv, jsonschema.
This skill helps you design correct, strict, and maintainable JSON Schemas for two dominant use cases: configuration files (validate user/operator input, fail fast with helpful messages) and APIs (contract for request/response bodies, often embedded in OpenAPI). It covers the type system, every important constraint keyword, schema composition, reuse via $ref/$defs, conditional validation, and turning raw validator output into actionable error messages.
Use the bundled material:
references/keywords.md— complete keyword reference (types, constraints, composition, applicators, annotations, draft differences) with copy-paste snippets.references/error-messages.md— patterns for clear, user-facing validation errors and how to map validator output to them.templates/config-schema.json— a strict, annotated starting point for a config-file schema.templates/api-schema.json— request/response schema pattern suitable for OpenAPIcomponents.schemas.scripts/validate.py— stdlib-only structural linter that flags the most common schema authoring mistakes; falls back tojsonschemaif installed for real validation.examples/config-walkthrough.md— sample config JSON turned into a finished schema with passing and failing instances.
Workflow
-
Pick the draft. Default to Draft 2020-12 for new schemas (
$schema: "https://json-schema.org/draft/2020-12/schema"). Use Draft-07 when targeting tooling that lags (olderajvconfigs, many OpenAPI 3.0 toolchains). OpenAPI 3.1 aligns with 2020-12. Note the differences: 2020-12 uses$defsandprefixItems/items; Draft-07 usesdefinitionsanditems(array)/additionalItems. Seereferences/keywords.md. -
Identify the root type and intent. Is this a config object, an API request, an API response, or a reusable component? Decide whether unknown keys are errors (config → almost always
"additionalProperties": false) or tolerated (forward-compatible APIs may allow them).
What ships with it
6 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.
- 1mo ago First seen · 106 lines · 100 tokens per session scan A fac9154cef8c
json-schema-author is a skill published in the GitHub repository JayRHa/AgentSkills (12 stars, last pushed 2mo ago), licensed MIT. It adds 100 tokens to every session and 2,088 once invoked, about $0.0004 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 2026-08-31.
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