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pantheon-ai/cfn-behavior-validator

Creates test stacks, analyzes CloudFormation events, and compares actual vs documented update behavior to validate whether resource property changes trigger replacement or in-place updates. Use when: a user wants to test if a CFN property change causes resource replacement; when investigating stack update behavior or "Update requires" documentation accuracy; when validating whether a workaround (e.g. hash-based logical IDs) is actually necessary; when questioning UpdateRequiresReplacement behavior for immutable properties; when empirical evidence is needed before an architectural decision involving CDK or CloudFormation stack updates.

Does it follow best practices?

Evaluation100%

1.12x

Agent success when using this tile

Validation for skill structure

Overview
Skills
Evals
Files

rubric.jsonevals/scenario-2/

{
  "context": "Tests whether the agent properly designs a minimal, isolated test stack with parameterization and defines observable success criteria for validation.",
  "type": "weighted_checklist",
  "checklist": [
    {
      "name": "Context parameterization",
      "description": "memory-test-stack.ts uses this.node.tryGetContext() or similar to drive the memory configuration",
      "max_score": 15
    },
    {
      "name": "Minimal resources",
      "description": "memory-test-stack.ts contains only Lambda function and essential dependencies (IAM role), no unrelated resources like S3 buckets, DynamoDB tables, or API Gateway",
      "max_score": 15
    },
    {
      "name": "Single property focus",
      "description": "The stack is designed to isolate testing the memory property specifically, not multiple Lambda properties",
      "max_score": 10
    },
    {
      "name": "Observable criteria defined",
      "description": "test-execution-plan.md defines specific CloudFormation events to look for (e.g., DELETE + CREATE for replacement)",
      "max_score": 15
    },
    {
      "name": "Success criteria explicit",
      "description": "test-execution-plan.md explicitly states what outcomes indicate replacement vs in-place update",
      "max_score": 15
    },
    {
      "name": "Verification method",
      "description": "test-execution-plan.md describes how to verify results (e.g., checking function ARN, inspecting CFN events)",
      "max_score": 15
    },
    {
      "name": "Valid CDK syntax",
      "description": "memory-test-stack.ts uses valid CDK v2 syntax (imports from 'aws-cdk-lib', extends cdk.Stack)",
      "max_score": 15
    }
  ]
}

Install with Tessl CLI

npx tessl i pantheon-ai/cfn-behavior-validator

evals

SKILL.md

tile.json