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Evals

Agent evaluation framework based on Anthropic's best practices. USE WHEN eval, evaluate, test agent, benchmark, verify behavior, regression test, capability test. Includes three grader types (code-based, model-based, human), transcript capture, pass@k/pass^k metrics, and ALGORITHM integration.

SKILL.md

Full skill instructions

Customization

Before executing, check for user customizations at: ~/​.claude/​skills/​CORE/​USER/​SKILLCUSTOMIZATIONS/​Evals/

If this directory exists, load and apply any PREFERENCES.md, configurations, or resources found there. These override default behavior. If the directory does not exist, proceed with skill defaults.

🚨 MANDATORY: Voice Notification (REQUIRED BEFORE ANY ACTION)

You MUST send this notification BEFORE doing anything else when this skill is invoked.

  1. Send voice notification:

    curl -s -X POST http://localhost:8888/notify \
      -H "Content-Type: application/​json" \
      -d '{"message": "Running the WORKFLOWNAME workflow in the Evals skill to ACTION"}' \
      > /​dev/​null 2>&1 &
    
  2. Output text notification:

    Running the **WorkflowName** workflow in the **Evals** skill to ACTION...
    

This is not optional. Execute this curl command immediately upon skill invocation.

Evals - AI Agent Evaluation Framework

Comprehensive agent evaluation system based on Anthropic's "Demystifying Evals for AI Agents" (Jan 2026).

Key differentiator: Evaluates agent workflows (transcripts, tool calls, multi-turn conversations), not just single outputs.


When to Activate

  • "run evals", "test this agent", "evaluate", "check quality", "benchmark"
  • "regression test", "capability test"
  • Compare agent behaviors across changes
  • Validate agent workflows before deployment
  • Verify ALGORITHM ISC rows
  • Create new evaluation tasks from failures

Core Concepts

Three Grader Types

TypeStrengthsWeaknessesUse For
Code-basedFast, cheap, deterministic, reproducibleBrittle, lacks nuanceTests, state checks, tool verification
Model-basedFlexible, captures nuance, scalableNon-deterministic, expensiveQuality rubrics, assertions, comparisons
HumanGold standard, handles subjectivityExpensive, slowCalibration, spot checks, A/​B testing

Evaluation Types

TypePass TargetPurpose
Capability~70%Stretch goals, measuring improvement potential
Regression~99%Quality gates, detecting backsliding

Key Metrics

  • pass@k: Probability of at least 1 success in k trials (measures capability)
  • pass^k: Probability all k trials succeed (measures consistency/​reliability)

Workflow Routing

TriggerWorkflow
"run evals", "evaluate suite"Run suite via Tools/​AlgorithmBridge.ts
"log failure"Log failure via Tools/​FailureToTask.ts log
"convert failures"Convert to tasks via Tools/​FailureToTask.ts convert-all
"create suite"Create suite via Tools/​SuiteManager.ts create
"check saturation"Check via Tools/​SuiteManager.ts check-saturation

Quick Reference

CLI Commands

# Run an eval suite
bun run ~/​.claude/​skills/​Evals/​Tools/​AlgorithmBridge.ts -s <suite>

# Log a failure for later conversion
bun run ~/​.claude/​skills/​Evals/​Tools/​FailureToTask.ts log "description" -c category -s severity

# Convert failures to test tasks
bun run ~/​.claude/​skills/​Evals/​Tools/​FailureToTask.ts convert-all

# Manage suites
bun run ~/​.claude/​skills/​Evals/​Tools/​SuiteManager.ts create <name> -t capability -d "description"
bun run ~/​.claude/​skills/​Evals/​Tools/​SuiteManager.ts list
bun run ~/​.claude/​skills/​Evals/​Tools/​SuiteManager.ts check-saturation <name>
bun run ~/​.claude/​skills/​Evals/​Tools/​SuiteManager.ts graduate <name>

ALGORITHM Integration

Evals is a verification method for THE ALGORITHM ISC rows:

# Run eval and update ISC row
bun run ~/​.claude/​skills/​Evals/​Tools/​AlgorithmBridge.ts -s regression-core -r 3 -u

ISC rows can specify eval verification:

| # | What Ideal Looks Like | Verify |
|---|----------------------|--------|
| 1 | Auth bypass fixed | eval:auth-security |
| 2 | Tests all pass | eval:regression |

Available Graders

Code-Based (Fast, Deterministic)

GraderUse Case
string_matchExact substring matching
regex_matchPattern matching
binary_testsRun test files
static_analysisLint, type-check, security scan
state_checkVerify system state after execution
tool_callsVerify specific tools were called

Model-Based (Nuanced)

GraderUse Case
llm_rubricScore against detailed rubric
natural_language_assertCheck assertions are true
pairwise_comparisonCompare to reference with position swap

Domain Patterns

Pre-configured grader stacks for common agent types:

DomainPrimary Graders
codingbinary_tests + static_analysis + tool_calls + llm_rubric
conversationalllm_rubric + natural_language_assert + state_check
researchllm_rubric + natural_language_assert + tool_calls
computer_usestate_check + tool_calls + llm_rubric

See Data/​DomainPatterns.yaml for full configurations.


Task Schema (YAML)

task:
  id: "fix-auth-bypass_1"
  description: "Fix authentication bypass when password is empty"
  type: regression  # or capability
  domain: coding

  graders:
    - type: binary_tests
      required: [test_empty_pw.py]
      weight: 0.30

    - type: tool_calls
      weight: 0.20
      params:
        sequence: [read_file, edit_file, run_tests]

    - type: llm_rubric
      weight: 0.50
      params:
        rubric: prompts/​security_review.md

  trials: 3
  pass_threshold: 0.75

Resource Index

ResourcePurpose
Types/​index.tsCore type definitions
Graders/​CodeBased/Deterministic graders
Graders/​ModelBased/LLM-powered graders
Tools/​TranscriptCapture.tsCapture agent trajectories
Tools/​TrialRunner.tsMulti-trial execution with pass@k
Tools/​SuiteManager.tsSuite management and saturation
Tools/​FailureToTask.tsConvert failures to test tasks
Tools/​AlgorithmBridge.tsALGORITHM integration
Data/​DomainPatterns.yamlDomain-specific grader configs

Key Principles (from Anthropic)

  1. Start with 20-50 real failures - Don't overthink, capture what actually broke
  2. Unambiguous tasks - Two experts should reach identical verdicts
  3. Balanced problem sets - Test both "should do" AND "should NOT do"
  4. Grade outputs, not paths - Don't penalize valid creative solutions
  5. Calibrate LLM judges - Against human expert judgment
  6. Check transcripts regularly - Verify graders work correctly
  7. Monitor saturation - Graduate to regression when hitting 95%+
  8. Build infrastructure early - Evals shape how quickly you can adopt new models

Related

  • ALGORITHM: Evals is a verification method
  • Science: Evals implements scientific method
  • Browser: For visual verification graders