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 JMMonte/agentic-digital-twin --skill add-materialgit clone --depth 1 https://github.com/JMMonte/agentic-digital-twinWrote 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/jmmonte/agentic-digital-twin/add-material)<a href="https://agentmods.dev/skills/jmmonte/agentic-digital-twin/add-material"><img src="https://agentmods.dev/badge/skills/jmmonte/agentic-digital-twin/add-material.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 | $0.00131 | $0.00793 |
| Opus 5 | $0.00066 | $0.00396 |
| Sonnet 5 | $0.00026 | $0.00159 |
| Haiku 4.5 | $0.00013 | $0.00079 |
Grade A, and why
add-material 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 7d 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 — 57 lines — stays where its author put it; the contents beside it link to each section on GitHub.
add-material
Material properties are where a model hallucinates most dangerously — a wrong
modulus or a generic "CFRP" strength silently poisons every FEA and mass/CG
audit. This skill keeps them honest: design/materials.json is the source of
truth, and nothing goes in it without a citation.
Rules (non-negotiable)
- Never invent a value. If you don't have a primary source, say so and ask the user — do not fill a plausible number.
- Cite the source for every material: MMPDS (metals), CMH-17 (composites),
an ASM handbook, or a manufacturer datasheet (alloy and temper, or the
specific prepreg). Record it in the
sourcefield. verifiedflag. Setverified: falsefor "typical"/unconfirmed values; settrueonly after a human checks it against the cited source. Theguardrails-checkskill flags any audit input that is missing or unverified.- Composites: one entry per prepreg+layup, named accordingly (e.g.
T700-2510-UD-Vf57-quasi-iso). Cite Vf, layup, orientation; record anisotropy (E1/E2/G12/ν12, directional strengths). Generic "CFRP" is forbidden. - Allowables, not typicals, for safety-critical margins — prefer A-/B-basis statistical allowables over handbook averages.
- Fluids (CFD): never hardcode density/viscosity. Pull from CoolProp at the
real T/P, e.g.
PropsSI('D','T',288.15,'P',101325,'Air').
Procedure
- Read
design/materials.json. If the material already exists, reuse it. - Obtain real values from a citable source. No source → stop and ask the user.
- Add the entry with SI units, the
sourcecitation, andverifiedset honestly. For composites, include the prepreg/Vf/layup and directional props. - Make audits (
fea*, mass/CG) read the property FROMmaterials.json— never inline the number in a script. - Run
guardrails-check: it should report zero audit-used properties that are missing orverified: false(or surface them for the user to confirm).
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.
- 7d ago First seen · 57 lines · 131 tokens per session scan A 9fefb2df0db7
add-material is a skill published in the GitHub repository JMMonte/agentic-digital-twin (2 stars, last pushed 2mo ago), licensed MIT. It adds 131 tokens to every session and 793 once invoked, about $0.0007 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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