Spec-Driven Development: When Structure Helps and When It Becomes Tax

Tisha Chawla · Software Engineer at Microsoft

1. The Ambiguity Tax

The bottleneck in AI-assisted engineering is no longer code generation. It is intent preservation.

A human engineer can resolve ambiguity using product context, team memory, architectural taste, and accumulated judgment. A coding agent cannot assume that context unless it is written somewhere durable. When intent only exists in chat history, the model fills the gaps with plausible assumptions. Some assumptions are harmless. Others shape the architecture before anyone notices they were wrong.

I call this the ambiguity tax: the rework, context drift, and architectural fragmentation caused by vague requirements entering an automated coding loop. IBM describes related failure modes in AI-assisted development, including context drift and fragmentation when generated code lacks complete system context. The GitHub Blog makes the same underlying point from the agent side: coding agents should be treated more like literal-minded pair programmers that need unambiguous instructions, not like search engines.