drug-trajectory-analysis

drug-trajectory-analysis is a skill for Claude Code, Codex from learningmatter-mit/AtomisticSkills. It costs 39 tokens per session (1,297 once invoked), scanned A, original, MIT.

A tool for measuring how a small molecule behaves inside a protein during a molecular-dynamics simulation, which models atomic motion over time. It reports movement, flexibility, hydrogen bonds, contacts, and interaction patterns.

In plain words
What is it for?
Use it to analyze ligand movement, binding-pocket flexibility, hydrogen-bond persistence, contact occupancy, and protein–ligand interactions from simulation files.
Why use it?
It turns a long simulation into measurements that help show whether a molecule stays in a plausible binding position and lets you compare compounds.

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/drug-trajectory-analysis
Any agent
npx skills add learningmatter-mit/AtomisticSkills --skill drug-trajectory-analysis
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 drug-trajectory-analysis

README.md
[![agentmods](https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/drug-trajectory-analysis.svg)](https://agentmods.dev/skills/learningmatter-mit/atomisticskills/drug-trajectory-analysis)
Your own site
<a href="https://agentmods.dev/skills/learningmatter-mit/atomisticskills/drug-trajectory-analysis"><img src="https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/drug-trajectory-analysis.svg" alt="Measured on agentmods" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,297 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 $0.00039 $0.01297
Opus 5 $0.00019 $0.00648
Sonnet 5 $0.00008 $0.00259
Haiku 4.5 $0.00004 $0.00130

Measured 4d ago against content hash c507f38921d4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

drug-trajectory-analysis 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 4d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/analyze_trajectory.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/drug-trajectory-analysis/SKILL.md · 113 lines

How it starts

The opening of the file, as written. The whole thing — 113 lines — stays where its author put it; the contents beside it link to each section on GitHub.

drug-trajectory-analysis

Goal

To extract quantitative binding-mode descriptors from a protein-ligand MD trajectory, producing:

  • Ligand heavy-atom RMSD (pose stability)
  • Ligand center-of-mass drift
  • Binding-pocket residue RMSF (pocket flexibility)
  • Hydrogen bond persistence
  • Key contact occupancy
  • Protein-ligand interaction fingerprints (IFPs) over time

These outputs feed directly into go/no-go decisions about pose validity and can be used to compare refinement trajectories across compounds.

Instructions

1. Prepare inputs

Required:

2. Run trajectory analysis

# Env: drugmd-agent
python .agents/skills/drug-trajectory-analysis/scripts/analyze_trajectory.py \
  --topology md/system/complex_solvated.pdb \
  --trajectory md/run/production.dcd \
  --ligand_resname UNL \
  --pocket_cutoff 5.0 \
  --output_dir md/analysis/

Key parameters:

  • --ligand_resname: residue name of the ligand in the topology (default: UNL). Check the solvated PDB if unsure.
  • --pocket_cutoff: distance cutoff in Angstroms for defining pocket residues around the ligand in the first frame (default: 5.0).
  • --skip_frames: skip the first N frames as equilibration (default: 0).
  • --snapshots: render PyMOL binding pocket snapshots at 4 timepoints (requires pymol-open-source).

3. Output files

The script produces:

  • md/analysis/ligand_rmsd.csv: per-frame ligand heavy-atom RMSD (Angstroms)
  • md/analysis/ligand_com.csv: per-frame ligand COM relative to protein backbone COM
  • md/analysis/pocket_rmsf.csv: per-residue RMSF of pocket residues (Angstroms)
  • md/analysis/hbonds.csv: hydrogen bond donor-acceptor pairs and occupancy fractions
  • md/analysis/contacts.csv: residue-level contact occupancy fractions
  • md/analysis/interaction_fingerprints.csv: per-frame binary IFP matrix (requires ProLIF)
  • md/analysis/analysis_summary.json: summary statistics
  • md/analysis/plots/: directory with PNG plots (RMSD time series, COM drift, RMSF bar chart, contact occupancy, PyMOL binding pocket snapshots)

Read the full file on GitHub · 113 lines

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. 4d ago First seen · 113 lines · 39 tokens per session scan A c507f38921d4

Subscribe to this mod's changes

drug-trajectory-analysis is a skill published in the GitHub repository learningmatter-mit/AtomisticSkills (158 stars, last pushed yesterday), licensed MIT. It adds 39 tokens to every session and 1,297 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 2026-08-30.

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