Evals

Evals is a skill for Claude Code from danielmiessler/LifeOS. It costs 129 tokens per session (2,181 once invoked), scanned A, original, MIT.

A framework for testing whether an AI agent produces acceptable results. Each test gives the agent an input and checks its answer with either fixed code rules or another language model acting as a judge.

In plain words
What is it for?
Use it to define evaluation cases, run capability and regression test suites, and measure reliable success across repeated trials.
Why use it?
It turns vague impressions about agent quality into repeatable tests. Running cases multiple times also shows whether an agent is consistently correct or only succeeds occasionally.

Skill for Claude Code

Written for Claude Code: background in frontmatter. Also seen: reads .claude/ paths.

Good fit Use it to define evaluation cases, run capability and regression test suites, and measure reliable success across repeated trials.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/danielmiessler/lifeos/evals
About the project

LifeOS is an AI-assisted personal operating system that records a person’s goals, values, context, and current situation to help move them toward a desired future state. It supports work such as building applications, starting businesses, and creative projects. Its catalogue entries extend the system through skills, hooks, agents, and commands.

danielmiessler/LifeOS · 19,557 stars · on GitHub · ourlifeos.ai

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 danielmiessler/LifeOS --skill evals
Clone the repo
git clone --depth 1 https://github.com/danielmiessler/LifeOS

Made for: Claude Code.

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/skills/danielmiessler/lifeos/evals/github.svg)](https://agentmods.dev/skills/danielmiessler/lifeos/evals)
Your own site
<a href="https://agentmods.dev/skills/danielmiessler/lifeos/evals"><img src="https://agentmods.dev/badge/skills/danielmiessler/lifeos/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/skills/danielmiessler/lifeos/evals"><img src="https://agentmods.dev/badge/skills/danielmiessler/lifeos/evals.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 129 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,181 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
  • Snyk pass 7 Sept 2026
  • 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 $0.00129 $0.02181
Opus 5.5 $0.00052 $0.00872
Sonnet 5.5 $0.00026 $0.00436
Haiku 4.5 $0.00013 $0.00218

Measured 1mo ago against content hash 0d317edd544c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 1mo ago.

The scan reads SKILL.md. This mod also ships 28 executable files (Graders/Base.ts, Graders/CodeBased/BinaryTests.ts, Graders/CodeBased/index.ts, …), 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.

LifeOS/install/skills/Evals/SKILL.md · 114 lines

How it starts

The opening of the file, as written. The whole thing — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Evals — Assertion-First AI Evaluation

What it is

An eval gives an AI an input, then applies assertions to its output to measure success (Anthropic's definition). A case is {id, prompt, assert:[...]}. Each assertion is either deterministic (code, fast/free) or model-graded (an LLM judge). Cases run multiple trials; we report pass^k (all trials pass — the honest metric for a reliability-critical agent) and pass@k (any trial passes). Everything routes through Inference.ts — subscription-billed, no API-key path, no external deps.

Grounded in Anthropic's current doctrine — Demystifying evals for AI agents, Define success criteria / develop tests, and the skill-creator {text, passed, evidence} assertion convention. The typed-assert layer is promptfoo-shaped but our own TS.

Freshness contract: "aligned to Anthropic's doctrine" is a live claim, not a snapshot. When designing a new suite class or touching the ## Doctrine section below, re-fetch the Demystifying-evals doc and flag where it has moved past what's encoded here. Advisory only — report divergence, never auto-adopt, and an unreachable URL never blocks a run.

The canonical path (v2)

Tool Role
Tools/Assertions.ts Deterministic assert engine: equals, contains, icontains, contains-all/any, regex, starts-with, ends-with, is-json, contains-json, max-length, min-length, each with not- negation. Sync, no model call.
Tools/Judge.ts Model-graded asserts llm-rubric (1–5 → 0–1, threshold) and llm-assert (NL assertions → TRUE/FALSE/UNKNOWN). Forced-structured JSON verdict, reason-then-score, distinct judge level, Unknown→miss escape hatch.
Tools/EvalRunner.ts Loads a suite, runs the agent-under-test per case (single-shot inference against the target system prompt), applies asserts, computes pass^k/pass@k, persists transcripts + latest.json.
Tools/SuiteManager.ts Suite listing + saturation tracking.
Tools/FailureToTask.ts Convert real failures into cases (seed from 20–50 real failures).

Read the full file on GitHub · 114 lines

Files

What ships with it

52 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. 1mo ago First seen · 114 lines · 129 tokens per session scan A 0d317edd544c

Subscribe to this mod's changes

Evals is a skill published in the GitHub repository danielmiessler/LifeOS (19,557 stars, last pushed 1mo ago), licensed MIT. It adds 129 tokens to every session and 2,181 once invoked, about $0.0005 per session on Opus 5.5. 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 2026-08-30.

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