Component Manifest
Token-efficient format (compact JSON / YAML) exposing a component's surface to an LLM via MCP, required props, allowed variants, states, a11y constraints, usage examples. Concept formalized by the Storybook team in the MCP sneak peek (March 2026): 'the manifest is what the agent sees first'. Instead of loading 200KB of TS source + MDX docs + stories, the agent receives a 2-5KB manifest containing the strict minimum to generate correct component usage. Massive context savings on 100+ component DS.
Strengths
- Major token savings, 100 components fit in context instead of loading 5
- Machine-readable format, auto-generation possible from TS types or Storybook stories
- Emerging standard, Storybook MCP + shadcn registry MCP + Knapsack MCP converge on this pattern
Limitations
- No universal standard in 2026, each MCP has its own manifest schema (JSON Schema, YAML, compacted TS types)
- Possible drift if manifest manually generated vs source code, automating generation is critical
Best for
- Design system manager writing custom MCP wanting a machine-readable schema consumable by all agents
- Team with 50+ component DS noticing agents fabricate variants, manifest forces LLM to see only what exists