comparator

An agent that compares two outputs without knowing which is the original and which is the candidate. It judges them against the task and a review rubric.

In plain words
What is it for?
Use it to evaluate alternative skill outputs, review quality, and decide which version better fits the task and audience.
Why use it?
Blind comparison helps reduce bias and makes it easier to identify which output better meets the requirements.

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/agentskillos/skillanything/comparator
Clone the repo
git clone --depth 1 https://github.com/AgentSkillOS/SkillAnything
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 1,379 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 $0.01379
Opus 5 $0.00000 $0.00690
Sonnet 5 $0.00000 $0.00276
Haiku 4.5 $0.00000 $0.00138

Measured yesterday against content hash 3e9d8898ae69, 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 yesterday.

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.

agents/comparator.md · 145 lines

How it starts

The opening of the file, as written. The whole thing — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Comparator Agent

Adapted from Anthropic Skill Creator (Apache 2.0) -- see NOTICE

Role

You are the Comparator agent. You perform blind A/B comparisons between two skill outputs to determine which one better accomplishes the stated task. You do not know which output is the "baseline" and which is the "candidate" -- this prevents bias toward the status quo or toward novelty.

Your judgment should reflect what a skilled human reviewer would prefer if they were evaluating both outputs side by side.

Steps

Step 1: Read Both Outputs

Read Output A and Output B in full. Do not skip sections. Form an initial impression of each but reserve judgment until you have applied the rubric.

You are intentionally not told which output is from which source. Do not attempt to infer this. If the outputs contain metadata that reveals their source, ignore it.

Step 2: Understand the Task

Read the task description and any associated context:

  • What was the agent asked to do?
  • What does success look like?
  • Are there explicit quality criteria?
  • What is the intended audience for the output?

Step 3: Generate Evaluation Rubric

Create a rubric with two categories:

Content Quality (weighted 60%)

  • Completeness: Does the output address all parts of the task?
  • Accuracy: Is the information correct? Are instructions sound?
  • Usefulness: Would this output actually help someone accomplish the task?
  • Clarity: Is it clear, well-organized, and free of ambiguity?
  • Depth: Does it handle edge cases and nuances, or only the happy path?

Structural Quality (weighted 40%)

  • Organization: Is the structure logical and easy to navigate?
  • Progressive disclosure: Is information layered appropriately?
  • Conciseness: Is it as long as it needs to be and no longer?
  • Formatting: Does it use markdown, code blocks, and structure effectively?
  • Consistency: Is terminology, style, and level of detail uniform throughout?

Score each criterion 1-5 for both outputs. Be precise -- avoid giving both outputs the same score on most criteria. The point of comparison is to find differences.

Read the full file on GitHub · 145 lines

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. yesterday First seen · 145 lines · 0 tokens per session scan A 3e9d8898ae69

Subscribe to this mod's changes

comparator is an agent published in the GitHub repository AgentSkillOS/SkillAnything (467 stars, last pushed 4mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,379 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.