scaffolding-llm-eval-harness

Scaffold a reproducible LLM evaluation harness with versioned prompts and JSONL results.

2|Updated May 23, 2026
One-click install
npx skills add https://github.com/rocklambros/rcs --skill scaffolding-llm-eval-harness
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: scaffolding-llm-eval-harness
Source: https://github.com/rocklambros/rcs/tree/main/skills/workflow/scaffolding-llm-eval-harness
Command: npx skills add https://github.com/rocklambros/rcs --skill scaffolding-llm-eval-harness

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill turns an empty directory into a reproducible LLM evaluation harness, preventing ad hoc scripts, drifting prompts, and incomparable benchmark runs.

Core Features & Use Cases

  • Structured harness scaffolding: Creates the core project files for running multi-scenario evaluations, including runner logic, prompt versioning, scenario storage, and comparison tooling.
  • Comparable result tracking: Enforces revision-pinned model IDs, canonical dataset hashing, optional judge-model grading, and JSONL result rows so outputs can be compared across runs.
  • Practical evaluation workflows: Fits jailbreak testing, prompt comparisons, fine-tune deltas, summarization checks, and other fixed-test-set LLM evaluation pipelines.
  • Guardrails and validation: Refuses to overbuild for one-shot API calls and redirects non-LLM classifier or retrieval evaluations to more appropriate workflows.

Quick Start

Ask this skill to scaffold a versioned LLM evaluation harness for your scenario set, candidate models, and optional judge model.

Frequently Asked Questions about scaffolding-llm-eval-harness

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

FAQPage Schema
How do I build a reproducible LLM evaluation harness from scratch?

A reproducible LLM evaluation harness prevents incomparable benchmark runs by enforcing versioned prompts, revision-pinned model IDs, and dataset hashing. It replaces ad hoc scripts with a structured scenario schema, ensuring run-to-run comparability.

How do I compare candidate prompts and fine-tunes across multiple scenarios?

You can compare candidate prompts and fine-tunes by running multi-scenario evaluations using a canonical scenario schema. The harness outputs JSONL result rows, enabling direct performance comparisons across different model revisions and prompt versions.

What is the best way to track prompt versioning and dataset hashing for LLM evals?

The best way to track prompt versioning and dataset hashing is to use a structured evaluation harness that stores canonical scenarios and pins model revisions. This logs JSONL result rows for consistent benchmark tracking.

Can I use a judge model to grade LLM evaluation runs?

Yes, you can use an optional judge model to grade LLM evaluation runs. The harness scaffolding supports integrating judge models alongside revision-pinned candidate models to automate scoring for complex scenarios like jailbreak testing or summarization.

Does this LLM evaluation harness work for RAG and jailbreak testing?

Yes, this LLM evaluation harness works for RAG and jailbreak testing, along with summarization checks and fixed-test-set pipelines. It structures multi-scenario comparisons to validate guardrails and prompt effectiveness across these specific workflows.

When should I not use a structured harness for LLM evaluation?

You should not use a structured LLM evaluation harness for one-shot API calls or non-LLM classifier and retrieval evaluations. The scaffolding refuses to overbuild for single requests and redirects non-LLM tasks to more appropriate workflows.