mat-db-nist-janaf

mat-db-nist-janaf is a skill for Claude Code, Codex from learningmatter-mit/AtomisticSkills. It costs 30 tokens per session (499 once invoked), scanned A, original, MIT.

A query tool for experimental thermochemistry from the NIST Chemistry WebBook and JANAF tables. It retrieves temperature-dependent values such as formation enthalpy, entropy, and heat capacity for chemical formulas.

In plain words
What is it for?
Fetching thermochemical data for elements and compounds and saving the results as JSON.
Why use it?
It saves time when looking up standard reference measurements for comparison with simulations.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit Fetching thermochemical data for elements and compounds and saving the results as…

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Install with agentmods
npx agentmods add skills/learningmatter-mit/atomisticskills/mat-db-nist-janaf
Install

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.

Any agent
npx skills add learningmatter-mit/AtomisticSkills --skill mat-db-nist-janaf
Clone the repo
git clone --depth 1 https://github.com/learningmatter-mit/AtomisticSkills

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for mat-db-nist-janaf

README.md
[![agentmods](https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/mat-db-nist-janaf.svg)](https://agentmods.dev/skills/learningmatter-mit/atomisticskills/mat-db-nist-janaf)
Your own site
<a href="https://agentmods.dev/skills/learningmatter-mit/atomisticskills/mat-db-nist-janaf"><img src="https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/mat-db-nist-janaf.svg" alt="Measured on agentmods" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 499 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00030 $0.00499
Opus 5 $0.00015 $0.00249
Sonnet 5 $0.00006 $0.00100
Haiku 4.5 $0.00003 $0.00050

Measured 3d ago against content hash a577cfad3574, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

mat-db-nist-janaf 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 3d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/query_janaf.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

.agents/skills/mat-db-nist-janaf/SKILL.md · 40 lines

What it actually says

mat-db-nist-janaf

Goal

To query experimental temperature-dependent thermodynamic properties and standard states (e.g. Standard Enthalpy of Formation $\Delta_f H^\circ_{298}$, Standard Entropy $S^\circ_{298}$, and $C_p$) from the NIST Chemistry WebBook and JANAF tables for benchmarking against DFT/MLIP calculations.

Instructions

Step 1. Query Thermochemistry Data

Use the query_janaf.py script to fetch thermodynamic data for a given chemical formula. The script automatically searches the WebBook for the closest matching standard element or compound and parses the HTML tables to extract the gas-phase or condensed-phase standard thermochemistry values.

# Env: base-agent
python .agents/skills/mat-db-nist-janaf/scripts/query_janaf.py <formula> <output_json>

Parameters:

  • formula: The chemical formula to query (e.g., CH4, CO2, H2O).
  • output_json: Path to the output JSON file where results will be stored.

Constraints

  • Environments: The scripts require the base-agent Conda environment.
  • Scraping Dependability: This script utilizes HTML scraping (beautifulsoup4). If the NIST WebBook layout changes in the future, the table selectors may need to be updated.
  • Isotopes: By default, the script skips explicitly isotopically-labelled variants (unless it's the only match) to return the standard natural-abundance compound.

References

  • Linstrom, P.J. and Mallard, W.G., Eds., NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg MD. URL
  • Chase, M.W., Jr., NIST-JANAF Thermochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951.

Author: Bowen Deng Contact: GitHub @learningmatter-mit

Files

What ships with it

3 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.

Changes

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.

  1. 3d ago First seen · 40 lines · 30 tokens per session scan A a577cfad3574

Subscribe to this mod's changes

mat-db-nist-janaf is a skill published in the GitHub repository learningmatter-mit/AtomisticSkills (161 stars, last pushed 3d ago), licensed MIT. It adds 30 tokens to every session and 499 once invoked, about $0.0002 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 2026-09-03.

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