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?
Evaluation — 100%
↑ 1.12xAgent success when using this tile
Validation for skill structure
Evaluation results
100%
8%Investigate SNS Subscription Endpoint Change Behavior
Complete validation workflow research and documentation
CFN docs lookup
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Community research
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Hypothesis stated
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Non-prod environment
75%
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Resource isolation
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Observable criteria
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CFN events inspection
25%
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Required report fields
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Behavior classification
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Workaround decision
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Without context: $0.7010 · 4m 3s · 23 turns · 1,491 in / 10,975 out tokens
With context: $0.7827 · 3m 5s · 31 turns · 28 in / 10,594 out tokens
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Design Test Infrastructure for Lambda Memory Configuration
CDK test stack design and parameterization
Context parameterization
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Minimal resources
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Single property focus
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Observable criteria defined
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Success criteria explicit
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Verification method
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Valid CDK syntax
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Without context: $0.3141 · 1m 36s · 12 turns · 13 in / 4,953 out tokens
With context: $0.5708 · 2m 3s · 22 turns · 69 in / 6,653 out tokens
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12%Execute DynamoDB Table Class Change Validation
Deployment commands and event inspection
Initial deployment command
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No approval flag
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Resource ARN recording
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Redeploy after change
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describe-stack-events command
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Resource type filter
0%
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Event field extraction
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Replacement indicators
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Update indicators
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Failure handling
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Without context: $0.3038 · 1m 31s · 8 turns · 57 in / 6,497 out tokens
With context: $0.3549 · 1m 58s · 13 turns · 1,524 in / 5,331 out tokens
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2%Handle Unexpected Behavior in RDS Instance Storage Change
Validation gates and repeatability testing
Initial deployment failure gate
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Unexpected behavior gate
83%
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Ambiguous results handling
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Repeat test condition
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Cleanup between tests
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Pre-repeat verification
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Additional data collection
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Multiple decision points
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Stop conditions clear
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Without context: $0.1918 · 1m 12s · 6 turns · 7 in / 3,871 out tokens
With context: $0.4897 · 1m 58s · 23 turns · 364 in / 5,814 out tokens
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33%Automate ECS Task Definition Memory Change Validation
Helper scripts and automation tools
Real-time event streaming
100%
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watch-cfn-events reference
25%
100%
Resource comparison mentioned
100%
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compare-resources reference
10%
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Before state capture
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After state capture
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Sequential workflow
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Without context: $0.2678 · 1m 14s · 10 turns · 11 in / 4,612 out tokens
With context: $0.5272 · 1m 47s · 23 turns · 20 in / 5,961 out tokens
Install with Tessl CLI
npx tessl i pantheon-ai/cfn-behavior-validator- Evaluated
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