SDD Tools: Kiro, Spec Kit, and Tessl ↗

sdd article intermediate sdd specifications ai-assisted-development

Author: Martin Fowler · Publication: martinfowler.com

Summary: Martin Fowler explores the three leading SDD tools, comparing their approaches to specification authoring, validation, and AI-driven implementation.

Editorial Notes

Fowler provides the architectural lens that most SDD articles lack. Rather than advocating for a specific tool, he dissects the design decisions behind Kiro (AWS), GitHub Spec Kit, and Tessl — what each one assumes about the developer workflow, how they handle specification granularity, and where they diverge on the question of spec-as-source versus spec-as-guide. Read this after you have hands-on experience with at least one tool to appreciate the trade-offs.

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Source: Spec-Driven Development

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Sdd Fundamentals

Link last verified: 2026-04-07