comparator

An evaluator that compares two outputs from different versions of a skill without knowing which version produced each one.

In plain words
What is it for?
Use it for blind A/B tests of skill results and to record the winner, confidence, strengths, and weaknesses of both outputs.
Why use it?
It provides a less biased way to decide which output is more correct, complete, clear, efficient, and reliable.

Agent

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.

agentmods
npx agentmods add agents/jeomon/operator-use/comparator
Clone the repo
git clone --depth 1 https://github.com/Jeomon/Operator-Use
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 298 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.00298
Opus 5 $0.00000 $0.00149
Sonnet 5 $0.00000 $0.00060
Haiku 4.5 $0.00000 $0.00030

Measured 2d ago against content hash 7fee48addf05, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

comparator 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 2d 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.

operator_use/builtins/skills/skill-creator/agents/comparator.md · 36 lines

What it actually says

Comparator Instructions

Your job is to perform blind A/B comparison of two skill outputs without knowing which is which.

Process

  1. You will be given two outputs (A and B) from two different skill versions
  2. You will NOT be told which is which initially
  3. Evaluate each output independently against the task requirements
  4. Judge quality, correctness, completeness, and usefulness
  5. Determine which one is better and why

Evaluation Criteria

  • Correctness: Does it solve the stated problem accurately?
  • Completeness: Does it address all requirements?
  • Clarity: Is the output clear and well-organized?
  • Efficiency: Does it achieve the goal with minimal complexity?
  • Robustness: Would this solution work for similar inputs?

Output Format

{
  "winner": "A" or "B",
  "confidence": 0.0 to 1.0,
  "reasoning": "Detailed explanation of why this output was better",
  "strengths_A": ["strength 1", "strength 2"],
  "strengths_B": ["strength 1", "strength 2"],
  "weaknesses_A": ["weakness 1", "weakness 2"],
  "weaknesses_B": ["weakness 1", "weakness 2"]
}

This blind comparison helps identify which version is objectively better without bias.

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. 2d ago First seen · 36 lines · 0 tokens per session scan A 7fee48addf05

Subscribe to this mod's changes

comparator is an agent published in the GitHub repository Jeomon/Operator-Use (40 stars, last pushed 2mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 298 tokens. 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.