Why AI Keeps Generating the Wrong Design Tokens and How I Fixed It with Figma's API

AI design system output is approximate by default. Wrong border radii, raw hex values, inconsistent tokens across 60 components. The fix isn't better prompts. Here's the structural change that made it exact using Figma's REST API. The fourth time I manually corrected the same border radius mistake in an AI-generated component, I stopped and asked why this kept happening. Not "what prompt would fix this?" The deeper question: why does every AI tool I tried get the structure right and the values wrong? The button was correct. The variants were there. The layout matched the Figma spec. But borderRadius: 8 when it should be borderRadius: '8px' . A spacing gap of 8 when the spec said 6 . The color #3B82F6 sitting in the file where semantic.button.primary should be. None of it wrong in a way that breaks the build. All of it wrong in a way that breaks the design system. After hitting this wall enough times, I realized the problem wasn't the AI. It was the question I was asking it. Why AI keeps generating the wrong Figma design tokens When you give an AI tool a Figma screenshot and ask it to produce a component, it does something reasonable: it interprets what it sees. The structure, the layout, the hierarchy - it gets most of that right. What it cannot get right is the token mapping. The AI doesn't know your semantic token file. It doesn't know that #3B82F6 maps to semantic.button.primary in your codebase. It doesn't know that your MUI setup multiplies numeric border radii by 4, which means borderRadius: 8 renders at 32px instead of 8px . So it approximates. Here's what that looks like in practice: What AI produces What the spec requires Why it's wrong borderRadius: 8 borderRadius: '8px' MUI multiplies numeric values by 4 gap: 8 gap: 6 Spacing value not extracted from Figma color: '#3B82F6' semantic.button.primary Raw hex instead of semantic token fontSize: 14 variant="MD_Medium" Typography token not resolved Across one component, these deviations are small. Across 60 comp