Eval Harness Kit

Eval Harness Kit

Overview

Create eval manifests, run tasks through an agent or command harness, and grade outputs with deterministic checks and optional LLM rubrics. The harness writes trajectories, metrics, and summaries to disk for repeatable analysis.

Quick start

1. Copy templates/​eval.manifest.json and edit tasks.
2. Run: python <CODEX_HOME>/​skills/​eval-harness-kit/​scripts/​run_eval.py --manifest <path> --run-id <id>
3. Inspect outputs in eval_runs/<run-id>/ and the summary JSON. Replace <CODEX_HOME> with your installed skill root (for example, ~/​.codex or C:\Users\you\.codex).

Single-turn vs agentic

• Single-turn: run_cmd writes a response file; graders check the output.
• Agentic: run_cmd invokes your agent harness; graders check output plus optional transcript files.

LLM rubric graders (optional)

• Use type: "llm_rubric" to call an external judge.
• Provide llm_judge_cmd in the manifest or judge_cmd per task.
• The judge must print JSON: {"passed": true|false, "score": 0.0-1.0, "details": "..."}.

Core Guidance

• Decide capability vs regression up front; keep regression suites near 100% pass rate.
• Prefer deterministic graders (exact/​regex/​json) and add LLM rubrics only when needed.
• Keep each trial isolated; write outputs and transcripts to the run directory.
• Log metrics for every trial: latency, exit code, stdout/​stderr sizes, output size.
• Use files as the memory boundary; do not paste large outputs into chat.

Trust / Permissions

• Always: Read local files, write run artifacts under eval_runs/.
• Ask: Any networked grader (LLM rubric), running commands that mutate state, or running tools outside the repo.
• Never: Exfiltrating credentials or running destructive commands without explicit user request.

Resources

• scripts/​run_eval.py: Execute evals from a manifest; writes JSONL results and summaries.
• scripts/​grade_response.py: Grade a single output against expected data.
• scripts/​compare_runs.py: Compare two results files and flag regressions.
• templates/​eval.manifest.json: Example manifest with single-turn and agentic tasks.
• references/​eval-roadmap.md: Guidance for building and maintaining eval suites.

Validation

• Run the example manifest; confirm eval_runs/<run-id>/​summary.json exists.
• Use compare_runs.py to compare two runs and verify regression detection.