large-data-read

large-data-read is a skill for Claude Code from iowarp/clio-kit. It costs 48 tokens per session (1,516 once invoked), scanned A, original, BSD-3-Clause.

A workflow for reading very large datasets with bounded reads and server-side summaries. A bounded read loads only a selected portion instead of the whole file.

In plain words
What is it for?
Use it to estimate data size, choose a manageable portion to read, or calculate supported statistics over HDF5 and Parquet data.
Why use it?
It helps avoid using excessive memory when you need a statistic or a small sample from a large dataset.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the clio-scientific-io-skills plugin — 3 skills shipped together

Good fit Use it to estimate data size, choose a manageable portion to read, or calculate supported statistics over HDF5 and Parquet data.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/iowarp/clio-kit/large-data-read
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 iowarp/clio-kit --skill large-data-read
Clone the repo
git clone --depth 1 https://github.com/iowarp/clio-kit

Made for: Claude Code.

Or install clio-scientific-io-skills, the plugin that ships this one along with the rest of its 3 skills.

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 large-data-read

README.md
[![agentmods](https://agentmods.dev/badge/skills/iowarp/clio-kit/large-data-read/github.svg)](https://agentmods.dev/skills/iowarp/clio-kit/large-data-read)
Your own site
<a href="https://agentmods.dev/skills/iowarp/clio-kit/large-data-read"><img src="https://agentmods.dev/badge/skills/iowarp/clio-kit/large-data-read/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 large-data-read

Your own site · 80×15
<a href="https://agentmods.dev/skills/iowarp/clio-kit/large-data-read"><img src="https://agentmods.dev/badge/skills/iowarp/clio-kit/large-data-read.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,516 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.
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 $0.00048 $0.01516
Opus 5.5 $0.00019 $0.00606
Sonnet 5.5 $0.00010 $0.00303
Haiku 4.5 $0.00005 $0.00152

Measured 9d ago against content hash 6040be85dc19, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

large-data-read 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.

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/clio-scientific-io-skills/skills/large-data-read/SKILL.md · 121 lines

How it starts

The opening of the file, as written. The whole thing — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Dataset Reading

Avoid transferring a whole dataset into the agent context to compute one number. Prefer a server-side reduction when it meets the requested coverage and accuracy. An exact reduction may still need to read every value.

Work out the size first

For a supplied HDF5 file, resolve its path and call open_file directly. Resource discovery scans configured directories; an empty listing does not mean that the supplied file is missing.

From get_shape and get_dtype: multiply the dimensions, multiply by the item size. A (2000, 2000, 500) array of float64 is 16 GB. Use it to choose a bounded read, and allow for temporary arrays and conversion overhead. Shape and dtype require separate tool calls.

If you want a statistic, do not read the data

Question Tool
Mean/min/max over all elements of each HDF5 dataset clio-hdf5:hdf5_aggregate_stats
Aggregate over a Parquet column clio-parquet:aggregate_column_tool
Discover structure across many HDF5 files clio-hdf5:hdf5_parallel_scan

hdf5_aggregate_stats reduces all elements of each selected dataset; it has no column or axis selector. Do not use its scalar mean as one column's mean in a multicolumn array, especially when columns have different units. Select a tool that implements the requested column reduction, or report the missing capability.

Open the HDF5 file before requesting aggregate statistics. For datasets larger than 500 MiB, hdf5_aggregate_stats may use a strided sample. Read the response's SAMPLED or FULL DATA label, processed/total element counts and coverage. Sample sum/count/min/max describe selected values only, not whole-dataset totals or bounds. Cross-dataset aggregation is omitted when any result is sampled. Striding can miss patterns; it is not a random representative sample. Older server versions may omit these labels, so verify coverage against the full shape. One- and multidimensional arrays use different stride logic. Use the actual response's counts and coverage; before a call, leave those quantities unverified. Multidimensional sampling also does not guarantee a small allocation. For exact results, use a separately verified chunked calculation with complete coverage or report that the available tool cannot establish the exact answer. Do not request thousands of hdf5_stream_data summaries to reconstruct an exact mean: they are rounded summaries, not lossless sums. Establish that a suitable local reader is available before choosing a fallback. Inspect its actual callable and selection/coverage behavior; an importable library or a source file containing the existing aggregate does not establish that a chunked column reader exists.

Read the full file on GitHub · 121 lines

Files

What ships with it

1 file 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. 9d ago First seen · 121 lines · 48 tokens per session scan A 6040be85dc19

Subscribe to this mod's changes

large-data-read is a skill published in the GitHub repository iowarp/clio-kit (30 stars, last pushed 8d ago), licensed BSD-3-Clause. It adds 48 tokens to every session and 1,516 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 2026-10-08.

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