rdf4j: Skill for Codex

.agent/skills/jmh-benchmark-compare/SKILL.md

jmh-benchmark-compare is a skill for Codex from eclipse-rdf4j/rdf4j. It costs 100 tokens per session (792 once invoked), scanned A, original, BSD-3-Clause.

A tool for comparing Java Microbenchmark Harness (JMH) results across multiple files.

In plain words
What is it for?
Use it to parse benchmark tables, compare matching tests, calculate score differences, filter regressions, and export reports.
Why use it?
It turns raw benchmark output into comparable results, making performance changes and regressions easier to find.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: mentions Codex.

This is eclipse-rdf4j/rdf4j's own configuration. It tells Codex how to work on rdf4j itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything rdf4j configures →

Reuse

Borrowing it

Nothing to install: this file belongs to eclipse-rdf4j/rdf4j. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/eclipse-rdf4j/rdf4j/main/.agent/skills/jmh-benchmark-compare/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/eclipse-rdf4j/rdf4j

Made for: 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 jmh-benchmark-compare

README.md
[![agentmods](https://agentmods.dev/badge/skills/eclipse-rdf4j/rdf4j/jmh-benchmark-compare/github.svg)](https://agentmods.dev/skills/eclipse-rdf4j/rdf4j/jmh-benchmark-compare)
Your own site
<a href="https://agentmods.dev/skills/eclipse-rdf4j/rdf4j/jmh-benchmark-compare"><img src="https://agentmods.dev/badge/skills/eclipse-rdf4j/rdf4j/jmh-benchmark-compare/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 jmh-benchmark-compare

Your own site · 80×15
<a href="https://agentmods.dev/skills/eclipse-rdf4j/rdf4j/jmh-benchmark-compare"><img src="https://agentmods.dev/badge/skills/eclipse-rdf4j/rdf4j/jmh-benchmark-compare.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 792 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
  • 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 $0.00100 $0.00792
Opus 5 $0.00050 $0.00396
Sonnet 5 $0.00020 $0.00158
Haiku 4.5 $0.00010 $0.00079

Measured 8d ago against content hash ef9fc56ee748, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

jmh-benchmark-compare 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 8d ago.

The scan reads SKILL.md. This mod also ships 4 executable files (scripts/jmh_benchmark_compare.py, scripts/jmh_compare_core.py, scripts/jmh_compare_export.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.

.agent/skills/jmh-benchmark-compare/SKILL.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

jmh-benchmark-compare

Use this skill when benchmark output comparison must be reproducible, sortable, and exportable.

Quick start

Run two-file comparison:

python3 .codex/skills/jmh-benchmark-compare/scripts/jmh_benchmark_compare.py \
  /path/run-a.txt /path/run-b.txt \
  --export-formats txt,md,csv,xlsx,html \
  --output-dir /tmp \
  --output-base jmh-compare

Sort by diff percent (descending):

python3 .codex/skills/jmh-benchmark-compare/scripts/jmh_benchmark_compare.py \
  run-a.txt run-b.txt \
  --sort-column "Diff % [run-b - run-a]" \
  --sort-desc \
  --export-formats md \
  --output /tmp/jmh-diff.md

Core behavior

  1. Detect first JMH table header line: line.startswith("Benchmark") and "Mode" in line and "Score" in line.
  2. Derive column boundaries from that header.
  3. Parse all following benchmark rows into an internal table.
  4. Match overlapping benchmark keys across files.
  5. Add derived columns: Diff Score [target - baseline], Diff % [target - baseline], Status [...].

Default key columns are all columns except Cnt, Score, Error. Override via --id-columns.

Inputs and overlap

  • Pass any mix of files and directories.
  • Directory entries are scanned for files that contain a JMH header.
  • --overlap-mode all keeps only rows present in all files.
  • --overlap-mode any keeps rows present in at least two files.
  • Baseline selection: --baseline <index-or-label>.

Filters and regression shortcuts

  • Hide tiny deltas: --min-deviation-pct 1.0
  • Show only regressions above threshold: --regressions-over-pct 3.0
  • Control direction interpretation: --score-direction auto|higher|lower

Historical analysis

Analyze trends across many runs:

python3 .codex/skills/jmh-benchmark-compare/scripts/jmh_benchmark_compare.py \
  /path/bench-history \
  --recursive \
  --glob "*.txt" \
  --timestamp-source auto \
  --analyze-over-time \
  --regressions-over-pct 2.5 \
  --export-formats html,csv \
  --output-dir /tmp \
  --output-base jmh-history

Read the full file on GitHub · 98 lines

Files

What ships with it

6 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. 8d ago First seen · 98 lines · 100 tokens per session scan A ef9fc56ee748

Subscribe to this mod's changes

jmh-benchmark-compare is a skill published in the GitHub repository eclipse-rdf4j/rdf4j (412 stars, last pushed yesterday), licensed BSD-3-Clause. It adds 100 tokens to every session and 792 once invoked, about $0.0005 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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