rdkit

rdkit is a skill for Claude Code from K-Dense-AI/scientific-agent-skills. It costs 80 tokens per session (1,530 once invoked), scanned A, original, MIT.

A Python toolkit for working with molecular structures and chemical information. It can read formats such as SMILES and SDF, calculate properties, search structures, model reactions, and create 2D or 3D representations.

In plain words
What is it for?
Use it for drug-discovery and computational-chemistry tasks such as calculating molecular weight or LogP, finding substructures, comparing molecules, generating conformers, and analysing reactions.
Why use it?
Chemical software often needs many separate operations, from checking a molecule's structure to comparing it with other molecules. This provides those operations in one programmable toolkit.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

not rated 44krepo +1.5k today A scan Socket: passSnyk: passSkillSpector: pass 80 tokens original MIT

Good fit Use it for drug-discovery and computational-chemistry tasks such as calculating molecular weight or LogP, finding substructures, comparing molecules, generating conformers, and analysing reactions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/k-dense-ai/scientific-agent-skills/rdkit
About the project

Scientific Agent Skills is a collection of reusable procedures that give AI agents capabilities for scientific research across areas such as biology, chemistry, medicine, and drug discovery. It is used by researchers and by people building AI scientist workflows with compatible coding agents. The catalogue contains many of the project's skills and supporting instructions.

K-Dense-AI/scientific-agent-skills · 44,469 stars · on GitHub · arxiv.org

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 K-Dense-AI/scientific-agent-skills --skill rdkit
Clone the repo
git clone --depth 1 https://github.com/K-Dense-AI/scientific-agent-skills

Made for: Claude Code.

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 rdkit

README.md
[![agentmods](https://agentmods.dev/badge/skills/k-dense-ai/scientific-agent-skills/rdkit/github.svg)](https://agentmods.dev/skills/k-dense-ai/scientific-agent-skills/rdkit)
Your own site
<a href="https://agentmods.dev/skills/k-dense-ai/scientific-agent-skills/rdkit"><img src="https://agentmods.dev/badge/skills/k-dense-ai/scientific-agent-skills/rdkit/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for rdkit

Your own site · 80×15
<a href="https://agentmods.dev/skills/k-dense-ai/scientific-agent-skills/rdkit"><img src="https://agentmods.dev/badge/skills/k-dense-ai/scientific-agent-skills/rdkit.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 80 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,530 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. Third-party audits
  • Socket pass 18 May 2026
  • Snyk pass 18 May 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00080 $0.01530
Opus 5 $0.00040 $0.00765
Sonnet 5 $0.00016 $0.00306
Haiku 4.5 $0.00008 $0.00153

Measured 9d ago against content hash d87943f6d751, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

rdkit 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 9d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/molecular_properties.py, scripts/similarity_search.py, scripts/substructure_filter.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.

skills/rdkit/SKILL.md · 112 lines

How it starts

The opening of the file, as written. The whole thing — 112 lines — stays where its author put it; the contents beside it link to each section on GitHub.

RDKit Cheminformatics Toolkit

Overview

RDKit is a comprehensive cheminformatics library providing Python APIs for molecular analysis and manipulation. This skill provides guidance for reading/writing molecular structures, calculating descriptors, fingerprinting, substructure searching, chemical reactions, 2D/3D coordinate generation, and molecular visualization. Use this skill for drug discovery, computational chemistry, and cheminformatics research tasks.

Current baseline (checked 2026-06-07): RDKit 2026.03.3 is the latest GitHub/PyPI release (rdkit 2026.3.3 on PyPI). Official installation docs continue to recommend conda-forge for most users, while cross-platform PyPI wheels are published under the rdkit package name. rdkit-pypi is the old PyPI package name and should only appear when maintaining legacy environments.

Installation and Setup

Use uv when installing into an existing Python environment:

uv pip install rdkit

For reproducible chemistry environments, especially when mixing compiled scientific packages, conda-forge remains the upstream recommendation:

conda create -c conda-forge -n my-rdkit-env rdkit
conda activate my-rdkit-env

Avoid installing both conda rdkit and PyPI rdkit/rdkit-pypi into the same environment unless you are deliberately debugging packaging behavior. Mixed installs can make it unclear which binary extension is being imported.

Core Capabilities

Twelve capability areas, each with worked code, are documented in references/core_capabilities.md:

# Area Covers
1 Molecular I/O and creation SMILES, MOL files and blocks, InChI, SDF and SMILES suppliers, multithreaded reading, writers
2 Sanitization and validation disabling automatic sanitization, manual and partial sanitization, detecting problems first
3 Analysis and properties atom and bond iteration, ring information and SSSR, chirality and stereochemistry, fragments
4 Descriptors MW, LogP, TPSA, H-bond donors/acceptors, rotatable bonds, aromatic rings, bulk calculation, drug-likeness
5 Fingerprints and similarity topological, Morgan/ECFP via rdFingerprintGenerator, MACCS, atom pair, torsion, Avalon; Tanimoto and other metrics; Butina clustering
6 Substructure searching SMARTS queries, match retrieval, and a library of common patterns
7 Chemical reactions reaction SMARTS, applying reactions, reaction fingerprints
8 2D and 3D coordinates depiction, template alignment, ETKDG embedding, force-field optimization, RMSD, constrained embedding
9 Visualization single and grid images, substructure highlighting, custom drawer options, Jupyter integration, fingerprint bit environments
10 Molecular modification explicit hydrogens, Kekulization, aromaticity, substructure replacement, charge neutralization
11 Hashes and standardization Murcko scaffold and canonical hashes, regioisomer hashes, randomized SMILES for augmentation
12 Pharmacophore and 3D features feature factories and feature extraction

Read the full file on GitHub · 112 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. 9d ago First seen · 112 lines · 80 tokens per session scan A d87943f6d751

Subscribe to this mod's changes

rdkit is a skill published in the GitHub repository K-Dense-AI/scientific-agent-skills (44,469 stars, last pushed today), licensed MIT. It adds 80 tokens to every session and 1,530 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 2026-09-03.

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