skill-evaluator

Run structured evaluation cycles comparing skill outputs against baselines with assertions and benchmarks.

Updated Jan 28, 2026
One-click install
npx skills add https://github.com/scanady/nexus-skills --skill skill-evaluator-scanady
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: skill-evaluator
Source: https://github.com/scanady/nexus-skills/tree/main/.agents/skills/skill-evaluator
Command: npx skills add https://github.com/scanady/nexus-skills --skill skill-evaluator-scanady

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes scripts (resource) and references (resource) components.

What problem does it solve? It answers whether an agent skill actually improves output quality by running controlled with-skill versus without-skill comparisons, grading results against evidence-based assertions, and aggregating pass rates, timing, and token costs into benchmarks. ## Core Features & Use Cases - Structured Eval Loop: Design test cases in evals.json, run each prompt with and without the skill in clean contexts, grade outputs, and iterate across versioned iteration directories. - Static Pre-Eval Analysis: Score executability, invocability, collision risk against neighbor skills, over-specification risk, and taxonomy fit before running any evals. - Programmatic Verification and Benchmarking: Use verify.py for mechanical assertion checks (file existence, valid JSON, counts) and benchmark.py to compute pass-rate, time, and token deltas. - Use Case: After writing a new CSV-analysis skill, run three test prompts with and without the skill, grade the outputs, and read benchmark.json to see the skill raised pass rate by 50 points at a known token cost. ## Quick Start Ask the agent to evaluate the skill in a given directory by designing test cases, running with-skill and baseline comparisons, and producing a benchmark report.

Frequently Asked Questions about skill-evaluator

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I evaluate whether an agent skill actually improves outputs?▼

Run each test prompt twice: once with the skill loaded and once without, in clean contexts. Grade both outputs against the same assertions, then compare pass rates, time, and token deltas in benchmark.json to measure the skill's real contribution.

How to write good assertions for skill evals?▼

Write assertions after seeing the first round of outputs, not before. Make them verifiable and specific, such as checking valid JSON, labeled chart axes, or minimum counts, and avoid vague or overly brittle wording checks.

What is a collision test case in skill evaluation?▼

A collision test case is a prompt squarely in a neighbor skill's territory, included when static analysis flags medium or high collision risk. The assertion verifies that the skill under test does not activate and the neighbor skill wins routing.

Can assertions be verified without an LLM judge?▼

Yes, mechanically checkable assertions like file existence, valid JSON or CSV, minimum counts, and string presence are verified by scripts/verify.py. Semantic assertions still require LLM grading with quoted evidence for each verdict.

When should I stop iterating on a skill using eval results?▼

Stop when human review feedback is consistently empty, pass-rate improvements between iterations fall below five percentage points, or the cost-quality delta is acceptable. Diminishing returns typically appear after three to five iterations.