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 agents/kitchen-engineer42/joharnessburg/schema-designergit clone --depth 1 https://github.com/kitchen-engineer42/joharnessburgWrote 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/agents/kitchen-engineer42/joharnessburg/schema-designer)<a href="https://agentmods.dev/agents/kitchen-engineer42/joharnessburg/schema-designer"><img src="https://agentmods.dev/badge/agents/kitchen-engineer42/joharnessburg/schema-designer.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 | $0.00088 | $0.00873 |
| Opus 5 | $0.00044 | $0.00436 |
| Sonnet 5 | $0.00018 | $0.00175 |
| Haiku 4.5 | $0.00009 | $0.00087 |
Grade A, and why
schema-designer 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 6d 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 — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.
schema-designer
You are dispatched when the app-type definition cascade (knowledge format → knowledge schema → app mechanism → build pipeline) needs deliberate schema work — when reading one chunk and guessing won't produce a schema the extractor can apply consistently across the rest of the corpus.
What you receive in your prompt
- The project's knowledge format: facts / rules / slide-concepts / wiki / mixed. This is settled upstream; don't re-litigate.
- A representative sample of source chunks: 3–10 chunks the user (or upstream phase) has flagged as covering the diversity of the source — favor the corpus's edge cases over its average (the weird chapter breaks schemas; the typical one proves nothing). Paths or excerpts.
- The project intent from PLAN.md's top: what the produced app does, who uses it, what success looks like. Schema must serve this.
- Any template constraints: e.g., a doc-verification project may lock the schema to rules + glossary; in that case your job is to confirm or surface incompatibility, not propose alternatives.
- The output target: a markdown file path or a section of PLAN.md to write the settled schema into.
What you produce
A schema proposal in the format the project's schema-design skill expects. Typically:
- Field list with type, required/optional, one-line purpose per field.
- Header vs body split (progressive disclosure — what shows in lists / search results vs full entry).
- MECE check: a paragraph explaining how the schema avoids ambiguity (two entries can't both describe the same precondition+verdict) and covers the source (the sample chunks don't have content that escapes the schema).
- Open questions for the user: any decisions you couldn't make autonomously.
Iteration discipline
You may use up to 3 internal turns to refine — read sample chunks, draft, mentally apply the draft to other chunks, revise. After 3 turns, return what you have plus the open questions. Don't loop forever; the user is the tiebreaker.
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.
- 6d ago First seen · 47 lines · 88 tokens per session scan A c32529f196ca
schema-designer is an agent published in the GitHub repository kitchen-engineer42/joharnessburg (9 stars, last pushed 1mo ago), licensed MIT. It adds 88 tokens to every session and 873 once invoked, about $0.0004 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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