chem-msms-predict

chem-msms-predict is a skill for Claude Code, Codex from learningmatter-mit/AtomisticSkills. It costs 51 tokens per session (1,540 once invoked), scanned A, original, MIT.

A prediction of a molecule’s liquid-chromatography tandem mass-spectrometry (LC-MS/MS) spectrum from its SMILES structure notation. It estimates fragment masses, intensities, and optional fragment structures.

In plain words
What is it for?
Use it to predict LC-MS/MS peaks, assign possible fragment ions, and compare the result with experimental spectra.
Why use it?
It provides a comparison spectrum when measured data is unavailable or when checking an experimental spectrum.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/learningmatter-mit/atomisticskills/chem-msms-predict
Any agent
npx skills add learningmatter-mit/AtomisticSkills --skill chem-msms-predict
Clone the repo
git clone --depth 1 https://github.com/learningmatter-mit/AtomisticSkills

Made for: Claude Code, Codex.

Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,540 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00051 $0.01540
Opus 5 $0.00026 $0.00770
Sonnet 5 $0.00010 $0.00308
Haiku 4.5 $0.00005 $0.00154

Measured 3d ago against content hash 409fda33fcd1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

chem-msms-predict 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 2 executable files (examples/predict_smiles.py, scripts/predict_msms.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/chem-msms-predict/SKILL.md · 139 lines

How it starts

The opening of the file, as written. The whole thing — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.

LC-MS/MS Spectrum Prediction

Goal

Predict the LC-MS/MS (tandem mass) spectrum of a molecule given its SMILES string using ICEBERG — a two-stage GNN that first generates a fragmentation DAG (fragment ions) and then predicts their intensities. Output is a predicted spectrum (m/z, intensity) with optional fragment SMILES assignments per peak.

When to Use This Skill

  • A SMILES string is known and a predicted LC-MS/MS spectrum (m/z vs intensity) is needed.
  • Fragment ion assignments (SMILES per peak) are required.
  • No reference spectrum exists, or comparison to a predicted spectrum is desired.
  • Companion skill chem-spectrum-matcher can compare predicted vs experimental spectra.

When NOT to Use This Skill

  • Experimental spectrum already available — use it directly; no prediction needed.
  • Only compound name known — first resolve to SMILES via drug-db-pubchem, then call this skill.
  • GC-MS or other MS types — ICEBERG is trained on LC-MS/MS only; flag a warning before proceeding.
  • Organometallics or MW > 1000 — predictions may be unreliable or fail due to unsupported element types.

Prerequisites

1. Download ICEBERG checkpoints

Download from coleygroup/ms-pred releases and place in downloads/:

downloads/
├── iceberg_dag_gen_msg_best.ckpt     # generator (stage 1)
└── iceberg_dag_inten_msg_best.ckpt   # intensity predictor (stage 2)

Flag error and stop if either checkpoint is missing.

2. Set up the conda environment

bash conda-envs/msms-agent/install.sh

The ms_pred Python package is installed from GitHub automatically by the install script.

Instructions

Step 1 — Run inference and generate spectrum

# Env: ms-gen
python .agents/skills/chem-msms-predict/scripts/predict_msms.py \
    --smiles "c1ccccc1C(=O)OCCN" \
    --gen_ckpt downloads/iceberg_dag_gen_msg_best.ckpt \
    --inten_ckpt downloads/iceberg_dag_inten_msg_best.ckpt \
    --collision_energies 20 40 \
    --adduct "[M+H]+" \
    --instrument "Orbitrap" \
    --output_dir results/msms_prediction

Read the full file on GitHub · 139 lines

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 · 139 lines · 51 tokens per session scan A 409fda33fcd1

Subscribe to this mod's changes

chem-msms-predict is a skill published in the GitHub repository learningmatter-mit/AtomisticSkills (154 stars, last pushed 8d ago), licensed MIT. It adds 51 tokens to every session and 1,540 once invoked, about $0.0003 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 2026-08-30.

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