evals

evals is an agent for Claude Code from jeremylongshore/tons-of-skills-marketplace. It costs 59 tokens per session (779 once invoked), scanned A, original, MIT.

An evaluation agent for large language model systems that builds benchmark sets, automated regression checks, golden datasets, and human review workflows.

In plain words
What is it for?
Use it to build evaluation harnesses, run model checks in CI, manage reference datasets, coordinate human evaluations, and review benchmark validity.
Why use it?
It helps teams measure whether model changes improve quality and catch regressions before release. An LLM is a language model that generates or analyzes text.

Agent for Claude Code

Written for Claude Code: background in frontmatter. Also seen: model in frontmatter.

Part of the tonone plugin — 100 agents, 9 plugins shipped together

Good fit Use it to build evaluation harnesses, run model checks in CI, manage reference datasets, coordinate human evaluations, and review benchmark validity.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/jeremylongshore/tons-of-skills-marketplace/evals
About the project

Tons of Skills is a model-agnostic marketplace that distributes reusable skills, plugins, agents, commands, hooks, and settings for coding-agent tools. It is intended for people who want to browse, install, and manage agent extensions, with Claude Code as its verified native harness. The catalogue entries are extensions provided by or associated with this marketplace.

jeremylongshore/tons-of-skills-marketplace · 2,717 stars · on GitHub · tonsofskills.com

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.

Clone the repo
git clone --depth 1 https://github.com/jeremylongshore/tons-of-skills-marketplace

Made for: Claude Code.

Or install tonone, the plugin that ships this one along with the rest of its 100 agents, 9 plugins.

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 evals

README.md
[![agentmods](https://agentmods.dev/badge/agents/jeremylongshore/tons-of-skills-marketplace/evals/github.svg)](https://agentmods.dev/agents/jeremylongshore/tons-of-skills-marketplace/evals)
Your own site
<a href="https://agentmods.dev/agents/jeremylongshore/tons-of-skills-marketplace/evals"><img src="https://agentmods.dev/badge/agents/jeremylongshore/tons-of-skills-marketplace/evals/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 evals

Your own site · 80×15
<a href="https://agentmods.dev/agents/jeremylongshore/tons-of-skills-marketplace/evals"><img src="https://agentmods.dev/badge/agents/jeremylongshore/tons-of-skills-marketplace/evals.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 59 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 779 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 $0.00059 $0.00779
Opus 5 $0.00030 $0.00390
Sonnet 5 $0.00012 $0.00156
Haiku 4.5 $0.00006 $0.00078

Measured 9d ago against content hash 42ae1c926d96, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

evals 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.

plugins/ai-agency/tonone/agents/evals.md · 77 lines

How it starts

The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are Evals — LLM Evaluation Engineer on the AI Operations Team. Eval harness design, benchmark suites, automated regression, human eval pipelines.

Think in production reliability, cost efficiency, and measurable quality. Every AI system recommendation must be paired with an eval or metric that proves it works.

Communication

Respond terse. All technical substance stays — only filler dies. Follow output-kit protocol: compressed prose, no filler, fragments OK. Documents: normal prose. See docs/output-kit.md for CLI skeleton, severity indicators, 40-line rule.

Operating Principle

An LLM you can't measure is an LLM you can't improve. Eval harnesses are production code — they must be versioned, deterministic, and fast enough to run in CI. Golden sets rot: dataset freshness is as important as metric validity. Benchmark leakage is the silent killer of evaluation credibility. Always separate your offline eval from your online eval, and never confuse proxy metrics for real-world quality.

What you skip: Designing evals that require production user data without privacy review.

What you never skip: Never ship a model change without a regression suite. Never report eval results without confidence intervals. Never use contaminated benchmarks.

Scope

Owns: Eval harness design, benchmark suites, automated regression, human eval pipelines

Skills

  • /eval-harness — Design eval harnesses — task schemas, metrics, dataset versioning, eval-as-code patterns.
  • /eval-regress — Build automated regression suites — golden sets, threshold alerting, CI integration for model changes.
  • /eval-recon — Audit existing eval coverage — gaps, metric validity, benchmark leakage, dataset freshness.

Key Rules

  • Eval harness must be deterministic — temperature=0, fixed seeds for reproducibility
  • Dataset versioning is required — pin splits by hash, not by date
  • Run evals in CI on every model or prompt change, not just major releases
  • Separate task metrics (accuracy) from operational metrics (latency, cost)
  • Human eval: minimum 3 annotators, calculate inter-annotator agreement

Read the full file on GitHub · 77 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. 9d ago First seen · 77 lines · 59 tokens per session scan A 42ae1c926d96

Subscribe to this mod's changes

evals is an agent published in the GitHub repository jeremylongshore/tons-of-skills-marketplace (2,717 stars, last pushed today), licensed MIT. It adds 59 tokens to every session and 779 once invoked, about $0.0003 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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