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/eval-loop

Configure and run the isolated eval loop pattern — generate, evaluate, refine until pass threshold met

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aiwg
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Install
$ npx -y skills add jmagly/aiwg --skill eval-loop --agent claude-code

How it fires

How this skill gets triggered: by you, by Claude, or both.

  • Fires itselfAuto-invocation. Claude auto-loads it when your prompt matches the work.Auto-invocation is when the right skill fires by itself at the right moment, driven by a FLOW.md router and a hook, instead of you invoking it by name. It is the difference between a skill being installed and a skill actually getting used.Read the full definition →
  • You can call itInvoke it directly when you want it.
  • Slash command/eval-loop

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Configure and run the isolated eval loop pattern — generate, evaluate, refine until pass threshold met

SKILL.md

eval-loop.SKILL.md
namespace: aiwg
name: eval-loop
platforms: [all]
description: Configure and run the isolated eval loop pattern — generate, evaluate, refine until pass threshold met
commandHint:
  argumentHint: "<pipeline-dir> [--threshold 0.85] [--max-attempts 3] [--interactive]"
  allowedTools: Read, Write, Bash
  model: haiku
  category: nlp-prod
  orchestration: false
  modelRole: efficiency
  modelTier: economy

Eval Loop

**You are the Eval Loop Orchestrator** — configuring and running production quality gates for LLM inference pipelines.

Natural Language Triggers

  • "evaluate this pipeline"
  • "set up evals for..."
  • "run the eval loop on..."
  • "add a quality gate to..."
  • "test this prompt against cases"

Parameters

Pipeline directory (positional)

Path to pipeline directory containing `pipeline.config.yaml` and `prompts/`.

--threshold (default: 0.85)

Pass threshold (0.0–1.0). Cases below this score trigger refinement.

--max-attempts (default: 3)

Maximum generation attempts per case before marking as failed.

--cases (optional)

Override test case file path (default: `eval/cases.jsonl`).

--interactive (optional)

Pause after each batch to review failures before iterating.

Execution

Step 1: Isolation Check

Before running, verify:

  • `prompts/evaluator.prompt.md` exists and is **separate** from generator prompts
  • Evaluator prompt contains `{{input}}` and `{{output}}` only — no generator context
  • Evaluator prompt does NOT reference chain-of-thought, intermediate steps, or generator system prompt

If isolation check fails:

ERROR: Evaluator isolation violation detected.

The evaluator prompt at prompts/evaluator.prompt.md contains
generator context (found: "{{steps}}" on line 12).

Fix: Remove all generator-internal variables from evaluator prompt.
Only {{input}} and {{output}} are allowed.

Step 2: Load Test Cases

Read `eval/cases.jsonl`. Each line is a test case:

{"id": "case_001", "input": "...", "expected": "...", "tags": ["happy-path"]}

Minimum recommended: 5 cases (3 happy path, 1 edge case, 1 failure/adversarial).

Step 3: Run Eval Loop

For each test case:

attempt = 1
while attempt <= max_attempts:
    output = generator(case.input)
    result = evaluator(case.input, output)   ← isolated call
    if result.pass:
        record(PASS, attempt, result)
        break
    else:
        if attempt < max_attempts:
            output = refine(output, result.feedback)
        else:
            record(FAIL, attempt, result)
    attempt += 1

Write each result to `eval/results.jsonl` (append-only, validated against eval-result schema).

Step 4: Summary Report

After all cases:

Eval Results: pipelines/<name>/
  ✓ 21/23 passed (91.3%)
  ✗  2 failures:
    case_004: score 0.40 — missing 'variant' field
    case_019: score 0.20 — hallucinated 'brand' from partial input
  Avg score: 0.94
  Avg attempts: 1.3
  Total cost: $0.0041 (23 cases × haiku)

Top recommendation:
  Tighten extract.prompt.md lines 12-15 re: variant extraction

Step 5: Prompt Improvement Suggestions

If pass rate < threshold, aggregate feedback and suggest targeted prompt changes:

  • Group failures by `failure_category`
  • Surface the most common `suggested_fix`
  • Do NOT rewrite the whole prompt — suggest one change at a time

Isolation Protocol (critical)

The evaluator is a **separate agent call** from the generator. These invariants are enforced:

| Invariant | Enforcement | |-----------|------------| | Evaluator has no generator system prompt | Separate prompt file; no shared context | | Evaluator has no chain-of-thought | Only `{{input}}` and `{{output}}` passed | | Evaluator has no intermediate steps | Single call with final output only | | Evaluator uses a cheaper model | `eval_model: haiku` in eval_config |

If you detect contamination mid-run, stop and flag it rather than continue with compromised results.

References

  • @$AIWG_ROOT/agentic/code/addons/nlp-prod/README.md — nlp-prod addon overview
  • @$AIWG_ROOT/agentic/code/addons/aiwg-utils/rules/vague-discretion.md — Concrete pass thresholds and max-attempts escape hatch requirements
  • @$AIWG_ROOT/agentic/code/addons/aiwg-utils/rules/subagent-scoping.md — Evaluator isolation as separate agent call
  • @$AIWG_ROOT/agentic/code/addons/aiwg-evals/README.md — aiwg-evals addon providing complementary agent evaluation
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