Design System Builder — Figma MCP Skill

Build professional-grade design systems in Figma that match code. This skill orchestrates multi-phase workflows across 20–100+ use_figma calls, enforcing quality patterns from real-world design systems (Material 3, Polaris, Figma UI3, Simple DS).

Prerequisites: The figma-use skill MUST also be loaded for every use_figma call. It provides Plugin API syntax rules (return pattern, page reset, ID return, font loading, color range). This skill provides design system domain knowledge and workflow orchestration.

Always include figma-generate-library in the comma-separated skillNames parameter when calling use_figma as part of this skill. If this skill was loaded via an MCP resource, you MUST prefix the name with resource: (e.g. resource:figma-generate-library). This is a logging parameter — it does not affect execution.

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1. The One Rule That Matters Most

For every phase, follow this communication contract.

Before starting a phase:

• Post a user-facing checklist titled Phase N Checklist.
• Include every task/subtask that will be attempted in that phase.
• Include the phase exit criteria.
• Do not begin mutating work for the phase until this checklist has been posted.
• If the phase requires explicit approval, ask for approval after the checklist and wait.

During execution:

• Before each major subsection, post a short update naming the exact section being worked on, using this format: Working on Phase N.X: <section name>
• Keep updates concise, but make the current work visible.
• When a subsection completes, mark it as completed in the running checklist if the interface supports checklist/status updates; otherwise mention completion in the next progress update.

At the end of each phase:

• Post a Phase N Summary with:
  • Completed tasks
  • Created or changed Figma objects
  • Validations performed
  • Decisions or conflicts resolved
  • Remaining risks or follow-ups
• Then show the required phase artifact for that phase and continue automatically.
• Only ask for explicit approval after Phase 0 or if a genuine decision fork arises (see Section 6). For Phases 1–4, the default is to continue automatically after the summary.

Stable Task IDs

Use one task ID format everywhere: P{phase}.{step}.

Rules:

• Use lettered step IDs only: P0.a, P0.b, P1.a, P3.d.
• Do not use plain bullet points for task lists.
• Every phase checklist, progress update, validation note, and phase summary MUST reference the same task IDs

No setup exception: Creating a new Figma file, importing a library, creating pages, variables, collections, styles, or components all count as creation/mutation. Do not treat any of them as harmless setup.

This is NEVER a one-shot task. Building a design system requires 20–100+ use_figma calls across multiple phases, with mandatory progress between them. Any attempt to create everything in one call WILL produce broken, incomplete, or unrecoverable results. Break every operation to the smallest useful unit, validate, get feedback, proceed.

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2. Mandatory Workflow

Work through the phases in order. Do not move to the next phase until the current phase's required actions and acceptance checks are complete. If a phase cannot pass, stop and report the blocker. Do not approximate, skip, or defer a failed phase unless the user explicitly approves the limitation. No best-effort substitutions. No quiet approximations. No handoff with missing source truth, missing visual truth, fake assets, approximate typography, broken interactions, or unverified states.

Phase 0: DISCOVERY (always first — no use_figma writes yet)

• 0a. Analyze codebase → extract tokens, components, naming conventions
• 0b. Inspect Figma file → pages, variables, components, styles, existing conventions
• 0c. Search subscribed libraries → use search_design_system for reusable assets
• 0d. Lock v1 scope → exact token set + component list recorded before any creation
• 0e. Map code → Figma → every conflict (code disagrees with Figma) resolved and recorded
• 0f. Print a gap analysis to chat: what exists in code but not Figma, what exists in Figma but not code, and every conflict from 0e with its resolution

Phase 1: FOUNDATIONS (tokens first — always before components)

• 1a. Create variable collections and modes
• 1b. Create primitive variables (raw values, 1 mode)
• 1c. Create semantic variables (aliased to primitives, mode-aware)
• 1d. Set scopes on ALL variables (never ALL_SCOPES)
• 1e. Set code syntax on ALL variables
• 1f. Create effect styles (shadows) and text styles (typography)
• 1g. Print a variable summary to chat: N collections, M variables, K modes, broken down by collection
• 1h. Print the style list to chat: every effect style and text style created, with names
• Exit criteria met: every token from the agreed plan exists, all scopes set, all code syntax set

Phase 2: FILE STRUCTURE (before components)

• 2a. Create page skeleton: Cover → Getting Started → Foundations → --- → Components → --- → Utilities
• 2b. Create foundations documentation pages (color swatches, type specimens, spacing bars)
• 2c. Capture a get_screenshot of every foundations page and print the page list to chat alongside the screenshots
• Exit criteria met: all planned pages exist, foundations docs are navigable

Phase 3: COMPONENTS (one at a time — never batch)

For EACH component (in dependency order: atoms before molecules), run the checklist below. Finish the current component before starting the next.

• 3a. Create dedicated page
• 3b. Build base component with auto-layout + full variable bindings
• 3c. Create all variant combinations (combineAsVariants + grid layout)
• 3d. Add component properties (TEXT, BOOLEAN, INSTANCE_SWAP)
• 3e. Link properties to child nodes
• 3f. Add page documentation (title, description, usage notes)
• 3g. Validate: get_metadata (structure) + get_screenshot (visual)
• 3h. Optional: lightweight Code Connect mapping while context is fresh
• Exit criteria met: variant count correct, all bindings verified, screenshot looks right

Phase 4: INTEGRATION + QA (final pass)

• 4a. Finalize all Code Connect mappings
• 4b. Accessibility audit (contrast, min touch targets, focus visibility)
• 4c. Naming audit (no duplicates, no unnamed nodes, consistent casing)
• 4d. Unresolved bindings audit (no hardcoded fills/strokes remaining)
• 4e. Final review screenshots of every page

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3. Critical Rules

Plugin API basics (from use_figma skill — enforced here too):

• Use return to send data back (auto-serialized). Do NOT wrap in IIFE or call closePlugin.
• Return ALL created/mutated node IDs in every return value
• Page context resets each call — always await figma.setCurrentPageAsync(page) at start. Call it at most once per script: each component or doc page is its own use_figma call. Never loop over figma.root.children and switch pages inside a mutating script — split that work into one focused call per target page (see figma-use → gotchas.md → Set current page once per use_figma call)
• figma.notify() throws — never use it
• Colors are 0–1 range, not 0–255
• Font MUST be loaded before any text write: await figma.loadFontAsync({family, style}). Use await figma.listAvailableFontsAsync() to discover available fonts and verify exact style strings — if a load fails, query available fonts to find the correct name or a fallback.

Design system rules:

1. Variables BEFORE components — components bind to variables. No token = no component.
2. Inspect before creating — run read-only use_figma to discover existing conventions. Match them.
3. One page per component (default) — exception: tightly related families (e.g., Input + helpers) may share a page with clear section separation.
4. Bind visual properties to variables (default) — fills, strokes, padding, radius, gap. Exceptions: intentionally fixed geometry (icon pixel-grid sizes, static dividers).
5. Scopes on every variable — NEVER leave as ALL_SCOPES. Background: FRAME_FILL, SHAPE_FILL. Text: TEXT_FILL. Border: STROKE_COLOR. Spacing: GAP. Radii: CORNER_RADIUS. Primitives: [] (hidden).
6. Code syntax on every variable — WEB syntax MUST use the var() wrapper: var(--color-bg-primary), not --color-bg-primary. Use the actual CSS variable name from the codebase. ANDROID/iOS do NOT use a wrapper.
7. Alias semantics to primitives — { type: 'VARIABLE_ALIAS', id: primitiveVar.id }. Never duplicate raw values in semantic layer.
8. Position variants after combineAsVariants — they stack at (0,0). Manually grid-layout + resize.
9. INSTANCE_SWAP for icons — never create a variant per icon. Cap variant matrices: if Size × Style × State > 30 combinations, split into sub-component.
10. Deterministic naming — use consistent, unique node names for idempotent cleanup and resumability. Track created node IDs via return values and the state ledger.
11. No destructive cleanup — cleanup scripts identify nodes by name convention or returned IDs, not by guessing.
12. Validate before proceeding — never build on unvalidated work. get_metadata after every create, get_screenshot after each component.
13. NEVER parallelize use_figma calls — Figma state mutations must be strictly sequential. Even if your tool supports parallel calls, never run two use_figma calls simultaneously.
14. Never hallucinate Node IDs — always read IDs from the state ledger returned by previous calls. Never reconstruct or guess an ID from memory.
15. Use the helper scripts — embed scripts from scripts/ into your use_figma calls. Don't write 200-line inline scripts from scratch.

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4. State Management (Required for Long Workflows)

getPluginData() / setPluginData() are NOT supported in use_figma. Use getSharedPluginData() / setSharedPluginData() instead (these ARE supported), or use name-based lookups and the state ledger (returned IDs).

Entity type	Idempotency key	How to check existence
Scene nodes (pages, frames, components)	setSharedPluginData('dsb', 'key', value) or unique name	node.getSharedPluginData('dsb', 'key') or page.findOne(n => n.name === 'Button')
Variables	Name within collection	(await figma.variables.getLocalVariablesAsync()).find(v => v.name === name && v.variableCollectionId === collId)
Styles	Name	getLocalTextStyles().find(s => s.name === name)

Tag every created scene node immediately after creation:

node.setSharedPluginData('dsb', 'run_id', RUN_ID);        // identifies this build run
node.setSharedPluginData('dsb', 'phase', 'phase3');        // which phase created it
node.setSharedPluginData('dsb', 'key', 'component/button');// unique logical key

State persistence: Do NOT rely solely on conversation context for the state ledger. Write it to disk:

/tmp/dsb-state-{RUN_ID}.json

Re-read this file at the start of every turn. In long workflows, conversation context will be truncated — the file is the source of truth.

Maintain a state ledger tracking:

{
  "runId": "ds-build-2024-001",
  "phase": "phase3",
  "step": "component-button",
  "entities": {
    "collections": { "primitives": "id:...", "color": "id:..." },
    "variables": { "color/bg/primary": "id:...", "spacing/sm": "id:..." },
    "pages": { "Cover": "id:...", "Button": "id:..." },
    "components": { "Button": "id:..." }
  },
  "pendingValidations": ["Button:screenshot"],
  "completedSteps": ["phase0", "phase1", "phase2", "component-avatar"]
}

Idempotency check before every create: query by name + state ledger ID. If exists, skip or update — never duplicate.

Resume protocol: at session start or after context truncation, run a read-only use_figma to scan all pages, components, variables, and styles by name to reconstruct the {key → id} map. Then re-read the state file from disk if available.

Continuation prompt (give this to the user when resuming in a new chat):

"I'm continuing a design system build. Run ID: {RUN_ID}. Load the figma-generate-library skill and resume from the last completed step."

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5. Library Discovery and search_design_system — Reuse Decision Matrix

Search FIRST in Phase 0, then again immediately before each component creation.

Start with get_libraries to understand what libraries are available before searching blindly:

// Discover all libraries accessible to the file
get_libraries({ fileKey })
// Returns:
//   libraries_added_to_file: [{ name, libraryKey, description, source }, ...]
//   libraries_available_to_add: [{ name, libraryKey, description, source }, ...]
//   libraries_available_to_add_next_offset: number | null

Use the returned libraryKey values to scope searches to specific libraries via includeLibraryKeys. This avoids noisy results when many libraries are available.

If libraries_available_to_add_next_offset is non-null, more org libraries are available — call get_libraries again with offset set to that value. Org libraries page in batches of 20; community UI kits only appear on the first page.

// Search across all libraries (default)
search_design_system({ query, fileKey, includeComponents: true, includeVariables: true, includeStyles: true })

// Search within a specific library only
search_design_system({ query, fileKey, includeLibraryKeys: ["lk-abc123..."], includeComponents: true })

Reuse if all of these are true:

• Component property API matches your needs (same variant axes, compatible types)
• Token binding model is compatible (uses same or aliasable variables)
• Naming conventions match the target file
• Component is editable (not locked in a remote library you don't own)

Rebuild if any of these:

• API incompatibility (different property names, wrong variant model)
• Token model incompatible (hardcoded values, different variable schema)
• Ownership issue (can't modify the library)

Wrap if visual match but API incompatible:

• Import the library component as a nested instance inside a new wrapper component
• Expose a clean API on the wrapper

Priority order: local existing → subscribed library import → unsubscribed UI Kit library from libraries_available_to_add (icons especially) → create new.

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6. Decision Forks

Ask the user when paths fork — when two or more reasonable answers exist and no clear winner comes from the codebase, the Figma file, or the locked plan. Don't silently default. Present each option with its tradeoff and your recommendation; pick only after the user steers.

When NOT to ask: if exactly one path is clearly correct from the source of truth (code, Figma file, agreed plan), take it. This section is for genuine ambiguity, not for offloading every decision.

Fork situation	What to surface	Example ask
Code ≠ Figma on a token, component, or value	Both versions side by side, with provenance (file/line vs node)	"Code says --color-bg-primary = #FFFFFF, Figma has color/bg/primary = #FAFAFA. Which wins?"
Subscribed library has a close-but-not-exact match	Library component summary + gap list	"Library has Button with no loading state. Reuse + wrap locally, or rebuild from scratch?"
Scope ambiguity at plan-lock (0d)	What's clearly in, what's clearly out, what's ambiguous	"Spec lists Button and Input; Field is referenced but not defined. In or out of v1?"

If the user rejects an option you already built on: fix before moving on. Never build on rejected work.

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7. Naming Conventions

Match existing file conventions. If starting fresh:

Variables (slash-separated):

color/bg/primary     color/text/secondary    color/border/default
spacing/xs  spacing/sm  spacing/md  spacing/lg  spacing/xl  spacing/2xl
radius/none  radius/sm  radius/md  radius/lg  radius/full
typography/body/font-size    typography/heading/line-height

Primitives: blue/50 → blue/900, gray/50 → gray/900

Component names: Button, Input, Card, Avatar, Badge, Checkbox, Toggle

Variant names: Property=Value, Property=Value — e.g., Size=Medium, Style=Primary, State=Default

Page separators: --- (most common) or ——— COMPONENTS ———

Full naming reference: naming-conventions.md

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8. Token Architecture

Complexity	Pattern
< 50 tokens	Single collection, 2 modes (Light/Dark)
50–200 tokens	Standard: Primitives (1 mode) + Color semantic (Light/Dark) + Spacing (1 mode) + Typography (1 mode)
200+ tokens	Advanced: Multiple semantic collections, 4–8 modes (Light/Dark × Contrast × Brand). See M3 pattern in token-creation.md

Standard pattern (recommended starting point):

Collection: "Primitives"    modes: ["Value"]
  blue/500 = #3B82F6, gray/900 = #111827, ...

Collection: "Color"         modes: ["Light", "Dark"]
  color/bg/primary → Light: alias Primitives/white, Dark: alias Primitives/gray-900
  color/text/primary → Light: alias Primitives/gray-900, Dark: alias Primitives/white

Collection: "Spacing"       modes: ["Value"]
  spacing/xs = 4, spacing/sm = 8, spacing/md = 16, ...

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9. Per-Phase Anti-Patterns

Phase 0 anti-patterns:

• ❌ Starting to create anything before scope is locked with user
• ❌ Ignoring existing file conventions and imposing new ones
• ❌ Skipping search_design_system before planning component creation

Phase 1 anti-patterns:

• ❌ Using ALL_SCOPES on any variable
• ❌ Duplicating raw values in semantic layer instead of aliasing
• ❌ Not setting code syntax (breaks Dev Mode and round-tripping)
• ❌ Creating component tokens before agreeing on token taxonomy

Phase 2 anti-patterns:

• ❌ Skipping the cover page or foundations docs
• ❌ Putting multiple unrelated components on one page

Phase 3 anti-patterns:

• ❌ Creating components before foundations exist
• ❌ Hardcoding any fill/stroke/spacing/radius value in a component
• ❌ Creating a variant per icon (use INSTANCE_SWAP instead)
• ❌ Not positioning variants after combineAsVariants (they all stack at 0,0)
• ❌ Building variant matrix > 30 without splitting (variant explosion)
• ❌ Importing remote components then immediately detaching them

General anti-patterns:

• ❌ Retrying a failed script without understanding the error first
• ❌ Using name-prefix matching for cleanup (deletes user-owned nodes)
• ❌ Building on unvalidated work from the previous step
• ❌ Parallelizing use_figma calls (always sequential)
• ❌ Guessing/hallucinating node IDs from memory (always read from state ledger)
• ❌ Writing massive inline scripts instead of using the provided helper scripts
• ❌ Starting Phase 3 because the user said "build the button" without completing Phases 0-2

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10. Reference Docs

Load on demand — each reference is authoritative for its phase:

Use your file reading tool to read these docs when needed. Do not assume their contents from the filename.

Doc	Phase	Required / Optional	Load when
discovery-phase.md	0	Required	Starting any build — codebase analysis + Figma inspection
token-creation.md	1	Required	Creating variables, collections, modes, styles
documentation-creation.md	2	Required	Creating cover page, foundations docs, swatches
component-creation.md	3	Required	Creating any component or variant
code-connect-setup.md	3–4	Required	Setting up Code Connect or variable code syntax
naming-conventions.md	Any	Optional	Naming anything — variables, pages, variants, styles
error-recovery.md	Any	Required on error	Script fails, multi-step workflow recovery, cleanup of abandoned workflow state

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11. Scripts

Reusable Plugin API helper functions. Embed in use_figma calls:

Script	Purpose
inspectFileStructure.js	Discover all pages, components, variables, styles; returns full inventory
createVariableCollection.js	Create a named collection with modes; returns {collectionId, modeIds}
createSemanticTokens.js	Create aliased semantic variables from a token map
createComponentWithVariants.js	Build a component set from a variant matrix; handles grid layout
bindVariablesToComponent.js	Bind design tokens to all component visual properties
createDocumentationPage.js	Create a page with title + description + section structure
validateCreation.js	Verify created nodes match expected counts, names, structure
cleanupOrphans.js	Remove orphaned nodes by name convention or state ledger IDs
rehydrateState.js	Scan file for all pages, components, variables by name; returns full {key → nodeId} map for state reconstruction