before-after-evaluation

before-after-evaluation is a skill for Codex from jeremylongworth-source/AgentSkills. It costs 48 tokens per session (314 once invoked), scanned A, original, MIT.

A method for comparing an agent's normal result with its result when a skill is enabled. It evaluates both against the same task criteria and records evidence, safety issues, and extra work.

In plain words
What is it for?
For running or documenting before-and-after skill evaluations, scoring outputs, and deciding whether to keep, revise, split, merge, defer, or retire a skill.
Why use it?
It helps determine whether a skill genuinely improves results, including regressions and unsafe assumptions, instead of judging it from one positive example.

Skill for Codex

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

Good fit For running or documenting before-and-after skill evaluations, scoring outputs, and deciding whether to keep, revise, split, merge, defer, or retire a skill.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/jeremylongworth-source/agentskills/before-after-evaluation
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 jeremylongworth-source/AgentSkills --skill before-after-evaluation
Clone the repo
git clone --depth 1 https://github.com/jeremylongworth-source/AgentSkills

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 before-after-evaluation

README.md
[![agentmods](https://agentmods.dev/badge/skills/jeremylongworth-source/agentskills/before-after-evaluation/github.svg)](https://agentmods.dev/skills/jeremylongworth-source/agentskills/before-after-evaluation)
Your own site
<a href="https://agentmods.dev/skills/jeremylongworth-source/agentskills/before-after-evaluation"><img src="https://agentmods.dev/badge/skills/jeremylongworth-source/agentskills/before-after-evaluation/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 before-after-evaluation

Your own site · 80×15
<a href="https://agentmods.dev/skills/jeremylongworth-source/agentskills/before-after-evaluation"><img src="https://agentmods.dev/badge/skills/jeremylongworth-source/agentskills/before-after-evaluation.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 314 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 $0.00314
Opus 5 $0.00024 $0.00157
Sonnet 5 $0.00010 $0.00063
Haiku 4.5 $0.00005 $0.00031

Measured 9d ago against content hash b316b0b9490f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

before-after-evaluation 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/before-after-evaluation/SKILL.md · 46 lines

What it actually says

Before/After Evaluation

Core Workflow

  1. Confirm the scenario, target artifact, acceptance criteria, and compared conditions.
  2. Summarize the baseline output and the skill-enabled output using the same criteria.
  3. Score improvements and regressions with the project rubric.
  4. Separate missing context from skill failure.
  5. Record safety issues, reviewer edits, validation evidence, and overhead.
  6. Recommend keep, revise, split, merge, defer, or retire.

Safety Rules

  • Do not hide regressions or unsafe assumptions because the skill helped other criteria.
  • Do not publish private prompts, customer data, or sensitive outputs in public reports.
  • Do not claim a skill works broadly from one easy scenario.
  • Require human review for high-risk domains and production-impacting outputs.

Deliverable Shape

For before/after reports, provide:

  • Scenario and target artifact
  • Baseline result summary
  • Skill-enabled result summary
  • Rubric scores
  • Improvements and regressions
  • Safety and evidence notes
  • Overhead notes
  • Promotion decision and follow-up changes

References

  • Read references/before-after-evaluation-checklist.md when preparing a before/after skill evaluation.
Files

What ships with it

2 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. 9d ago First seen · 46 lines · 48 tokens per session scan A b316b0b9490f

Subscribe to this mod's changes

before-after-evaluation is a skill published in the GitHub repository jeremylongworth-source/AgentSkills (1 stars, last pushed 6d ago), licensed MIT. It adds 48 tokens to every session and 314 once invoked, about $0.0002 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 2026-08-31.

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