cellxgene-census

cellxgene-census is a skill for Claude Code from K-Dense-AI/scientific-agent-skills. It costs 97 tokens per session (3,251 once invoked), scanned A, original, MIT.

A programmatic interface to the CZ CELLxGENE Census, a versioned collection of public single-cell and spatial transcriptomics data. Single-cell transcriptomics measures gene activity in individual cells; spatial transcriptomics also records where cells are located in tissue.

In plain words
What is it for?
Use it to find datasets, filter cells by type, tissue, or disease, retrieve expression data and embeddings, access source H5AD files, and compare reference atlases.
Why use it?
It lets researchers query selected cells, genes, and metadata without first downloading entire datasets. Versioned releases make analyses easier to reproduce.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Use it to find datasets, filter cells by type, tissue, or disease, retrieve expression data and embeddings, access source H5AD files, and compare reference atlases.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/k-dense-ai/scientific-agent-skills/cellxgene-census
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 · 50,453 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 cellxgene-census
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 cellxgene-census

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/k-dense-ai/scientific-agent-skills/cellxgene-census"><img src="https://agentmods.dev/badge/skills/k-dense-ai/scientific-agent-skills/cellxgene-census.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 97 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,251 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 2 Oct 2026
  • Snyk pass 2 Oct 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 $0.00097 $0.03251
Opus 5.5 $0.00039 $0.01300
Sonnet 5.5 $0.00019 $0.00650
Haiku 4.5 $0.00010 $0.00325

Measured 14d ago against content hash 123b66d6701c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cellxgene-census 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 14d 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.

Origin

Copies of this mod

4 near-identical copies found in the catalogue:

skills/cellxgene-census/SKILL.md · 335 lines

How it starts

The opening of the file, as written. The whole thing — 335 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CZ CELLxGENE Census

Overview

The CZ CELLxGENE Census provides programmatic access to a comprehensive, versioned collection of standardized single-cell and spatial transcriptomics data from CZ CELLxGENE Discover. This skill enables efficient querying and analysis of public Census releases without downloading whole datasets first.

The Census includes:

  • 217+ million total cells and 125+ million unique cells in the 2025-11-08 stable LTS release
  • 1,845 datasets in the 2025-11-08 stable LTS release
  • Human, mouse, marmoset, rhesus macaque, and chimpanzee data in the current schema
  • Standardized metadata (cell types, tissues, diseases, donors)
  • Raw gene expression matrices and source H5AD lookup/download helpers
  • Pre-calculated summary counts, embeddings, and spatial data
  • Integration with AnnData, Scanpy, TileDB-SOMA, TileDB-SOMA-ML, and other analysis tools

When to Use This Skill

This skill should be used when:

  • Querying single-cell expression data by cell type, tissue, or disease
  • Exploring available single-cell datasets and metadata
  • Training machine learning models on single-cell data
  • Performing large-scale cross-dataset analyses
  • Integrating Census data with scanpy or other analysis frameworks
  • Computing statistics across millions of cells
  • Accessing pre-calculated embeddings or model predictions

Installation and Setup

Install the Census API:

uv pip install "cellxgene-census==1.18.0"

For spatial workflows:

uv pip install "cellxgene-census[spatial]==1.18.0"

For PyTorch model training, use TileDB-SOMA-ML. The old cellxgene_census.experimental.ml loaders are absent from 1.18.0:

uv pip install "cellxgene-census==1.18.0" tiledbsoma-ml

Core Workflow Patterns

Eight patterns, each with code, are in references/core_workflow_patterns.md:

  1. Opening the Census — always pin census_version so an analysis stays reproducible.
  2. Exploring Census information — available datasets, cell counts, and summary tables.
  3. Querying expression data — small to medium scale into an AnnData.
  4. Large-scale queries — out-of-core processing when the slice will not fit in memory.
  5. Machine learning with PyTorch — TileDB-SOMA-ML data loaders.
  6. Spatial Census data — accessing spatial assays.
  7. Integration with Scanpy — handing a Census slice to a standard Scanpy workflow.
  8. Multi-dataset integration — combining datasets and handling batch effects.

Read the full file on GitHub · 335 lines

Files

What ships with it

4 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. 14d ago Changed · +18 lines 123b66d6701c
  2. 15d ago Changed · +16 lines 23e44c7d7799
  3. 1mo ago Changed · +17 lines 3e7cee2dc141
  4. 1mo ago First seen · 284 lines · 97 tokens per session scan A 9ce161d06d4c

Subscribe to this mod's changes

cellxgene-census is a skill published in the GitHub repository K-Dense-AI/scientific-agent-skills (50,453 stars, last pushed today), licensed MIT. It adds 97 tokens to every session and 3,251 once invoked, about $0.0004 per session on Opus 5.5. 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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