zarr-python

zarr-python is a skill for Claude Code from K-Dense-AI/scientific-agent-skills. It costs 59 tokens per session (2,359 once invoked), scanned A, original, MIT.

A guide to Zarr-Python, a library for storing large multidimensional arrays in compressed chunks. It supports parallel access and cloud storage, and works with common Python scientific-data tools.

In plain words
What is it for?
Use it for scientific arrays, imaging or sensor data, cloud-based storage, and workflows using NumPy, Dask, or Xarray.
Why use it?
It makes large numerical datasets easier to store, read, process, and share without handling them as one giant file.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Use it for scientific arrays, imaging or sensor data, cloud-based storage, and workflows using NumPy, Dask, or Xarray.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/k-dense-ai/scientific-agent-skills/zarr-python
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 · 53,578 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 zarr-python
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 zarr-python

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/k-dense-ai/scientific-agent-skills/zarr-python"><img src="https://agentmods.dev/badge/skills/k-dense-ai/scientific-agent-skills/zarr-python.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,359 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 1 Oct 2026
  • Snyk pass 1 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 $0.00059 $0.02359
Opus 5.5 $0.00024 $0.00944
Sonnet 5.5 $0.00012 $0.00472
Haiku 4.5 $0.00006 $0.00236

Measured 20d ago against content hash 1edaabfc3fc6, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

zarr-python 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 20d 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

1 near-identical copy found in the catalogue:

skills/zarr-python/SKILL.md · 189 lines

How it starts

The opening of the file, as written. The whole thing — 189 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Zarr Python

When to use

Use for chunked scientific arrays, hierarchical stores, codecs, sharding, partial reads, cloud object storage, and NumPy/Dask/Xarray interoperability. This community guide targets Zarr-Python 3.4.0, released 2026-09-15, with Python 3.12+. The package version and on-disk format are separate: this release reads/writes formats 2 and 3; new arrays default to format 3. Keep downstream packages that require zarr<3 in their own environments.

Install

uv pip install "zarr==3.4.0" "numpy==2.5.3"
# Optional remote backends and migration CLI:
uv pip install "zarr[remote,cli]==3.4.0" "fsspec==2026.9.0" "s3fs==2026.9.0" "gcsfs==2026.8.1"

Commit the project's resolved lockfile. Optional integration versions exercised here: Dask 2026.8.0, Xarray 2026.9.0, h5py 3.16.0, NumCodecs 0.17.0, obstore 0.11.1. Local examples below and in the references use tiny synthetic arrays; remote snippets are illustrative and require a real authorized store. This does not establish cloud permissions, production throughput, or compatibility of every downstream reader.

Workflow

  1. Inspect shape, dtype, axis names, coordinates, units, missing-value convention, format, codec availability, and intended readers. Preserve sample IDs and axis order.
  2. Choose chunks for actual selections and a memory budget. For sharding, choose shard dimensions that are multiples of chunk dimensions. Benchmark representative data.
  3. Create a new destination (overwrite=False or mode="w-"). Use mode="r" for inspection; "a" can create a missing store and "w" destroys existing content.
  4. Write bounded blocks. Assign one writer per stored chunk, or per shard when sharded; serialize metadata, append, and resize operations.
  5. Reopen read-only and compare values, dtype, shape, coordinates, units, masks and metadata. An unwritten or missing chunk normally reads as fill_value; a successful open alone does not prove data completeness.
  6. For a completed group hierarchy, optionally consolidate metadata. Format-3 consolidation is experimental; refresh it after metadata changes and verify the actual consumers. Publish a completed store only after validation.

Read the full file on GitHub · 189 lines

Files

What ships with it

7 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. 20d ago Changed · -74 lines · +7 tokens per session 1edaabfc3fc6
  2. 21d ago Changed · +4 lines 110105d3c029
  3. 1mo ago First seen · 259 lines · 52 tokens per session scan A 36f6900413be

Subscribe to this mod's changes

zarr-python is a skill published in the GitHub repository K-Dense-AI/scientific-agent-skills (53,578 stars, last pushed 2d ago), licensed MIT. It adds 59 tokens to every session and 2,359 once invoked, about $0.0002 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 2026-09-03.

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