MCP server framesmith

framesmith

An open-source MCP server that turns your AI coding agent into a capable UI designer. It gives the agent a visual canvas, a library of vetted design patterns, and a quality bar it must clear before showing you anything — so you review a real, non-slop design in the browser and agree on it before any framework code is written.

Contents: What it does · Capabilities · Viewer · Installation · Tools · Usage Example · Workflow · Development

Above: the framesmith viewer, showing the built-in pattern library — 11 vetted page archetypes an agent starts from, each carrying its live quality score and its designed state variants. Workspaces and projects sit in the sidebar; you browse canvases like design files.

What an agent actually ships

Every screen below was built end-to-end by an agent with framesmith's own vocabulary — one generate_design_system call each (a seed color + a personality), stamped patterns, real controls, and every quality gate cleared (score ≥ 95, stress-tested, both themes, and every state the evaluator demands designed):

Same machinery, different seed + personality: a light ops dashboard and a dark API console. Every color pair is AA by construction, every chart is data-bound (edit a value, not an SVG path), and the dark theme is generated — not inverted.

Not every screen is a dashboard. This checkout carries the commerce genre — the transactional counterpart to data — so the evaluator reads its line prices and total as the design rather than as fabricated data. It still cleared the same bar as the two screens above, including designed empty-basket and loading states.

Not every screen is a web page either. This one is declared type: "mobile", so it is judged as a phone screen: a 44px tap target on every button, row and tab, content clear of the status bar and home indicator, and a minimum body size. It started from the dashboard structure, which stamps its phone version on a mobile canvas, and is built from the phone primitives (status bar, nav bar, buttons, list rows, tab bar) with no hand-built device chrome, in 33 nodes. framesmith's test suite rebuilds it on every run.

MCP Client → stdio → framesmith server
                        ↓
              Scene Graph (in-memory JSON tree)
                        ↓
              HTML/CSS Renderer (inline styles)
                        ↓
              Puppeteer (headless Chromium → PNG)

What framesmith does

Left to itself, an AI agent tends to produce UI that looks AI-generated — generic spacing, no icons, a purple gradient by default, placeholder text that reads like placeholder text. framesmith closes that gap by moving design before code and holding it to a bar:

1. Start from taste, not a blank canvas. The agent stamps one of 11 vetted page patterns (dashboard, auth, pricing, settings, onboarding, and more), or on a phone canvas one of 6 mobile realisations built from the mobile primitives — each regression-tested to score > 95 with zero cliché tells under the neutral default theme and all four presets (a mobile realisation takes the presets' colours over a phone type scale, is also held to every personality's generated phone system, and raises no mobile-ruleset finding), and every structure (page and component alike) built entirely from type-role tokens so it re-voices under a generated design system instead of injecting stray pixel sizes, and hardened to survive hostile-length content (canvas_stress CLEAN) — then adapts it. A blank canvas is where slop comes from; a pattern is a non-slop starting point. (list_structures / apply_structure)
2. Use the whole toolkit — like a real UI does. Real icons (Lucide + Material Symbols), fonts resolved by name, real input controls (toggle / checkbox / radio / select), data-driven charts (line/bar/donut/sparkline, multi-series, bar emphasis), reusable components, and layered design tokens — never faked with Unicode glyphs, stray ellipses, or hand-drawn SVG paths standing in for a chart.
3. Evaluate, then self-correct. canvas_evaluate scores the design across five craft categories plus a cliché-tell detector, a state-coverage check (a data screen without designed empty/loading states isn't done), and a usability layer (hit-target floor, label association, honest action copy), and returns a READY / NOT READY directive. The agent resolves every warning and tell and only presents once it's READY — polishing to the bar is the agent's job, not yours.
4. Review in the browser, own the output. You browse canvases like design files, with a live quality inspector and design-system panel. Designs persist as open JSON checked into your repo — no proprietary format, no lock-in — and can be re-imported from shipped HTML to keep the design honest.

Capabilities at a glance

Area	What you get
Rendering	Scene graph → HTML/CSS → Puppeteer PNG · responsive breakpoints · real CSS grid (layout: "grid" + spans) for bento/editorial compositions · gradients, shadows, blur, glassmorphism · SVG paths · animations · data-driven charts (line/bar/donut/sparkline, multi-series, bar emphasis + in-SVG gradients)
Pattern library	11 vetted page archetypes + 6 mobile realisations + 14 component scaffolds, all scoring > 95 with zero cliché tells, typography built from type-role tokens (not literal pixel sizes), and stress-hardened to survive hostile-length content; taxonomy axes + a diversification signal so successive screens vary
Quality & taste	canvas_evaluate (8 categories incl. cliché tells, state coverage + usability floors) with a READY/NOT READY directive · canvas_autofix (mechanical fixes) · optional vision-model rubric critique + canvas_revise · canvas_add_variant clones a screen into a linked empty/loading/error state · canvas_stress content-perturbation testing (long text, i18n, big numbers, empty/many rows) · project_evaluate rolls up a project's screens for cross-screen consistency (radius/accent drift, token adoption, hand-copied chrome, state coverage) plus an optional multi-screen flow critique — advisory, never a gate
Design systems	generate_design_system: one seed + one personality (technical / editorial / soft / data-dense) → the complete design language — colors, curated font pairing, typography roles, radius/density stances, $elevation depth tokens (dark-aware), $motion defaults · layered $tokens (workspace ▸ project ▸ canvas) · style presets · DESIGN.md import · generate_scale derives a modular type + spacing scale from a named ratio (optional fluid clamp() sizes) · generate_color_system turns one seed color into OKLCH ramps + AA-checked semantic tokens, a categorical chart palette, and a tint layer for chips/tiles/badges, dark theme included · dual-theme rendering + evaluation (theme: "dark" on screenshot/export, both-theme contrast in canvas_evaluate with APCA advisory) · token-detachment lint re-attaches literals that drift from a token
Primitives	Lucide + Material Symbols icons · Google Fonts by name · real form controls · components with instance overrides — create_component promotes existing work, copy_nodes carries subtrees (and their component defs) across canvases
Import from code	canvas_import_html / canvas_import_url — token-mapped, structure-reconstructed · canvas_sync_from_url pixel drift · canvas_check_drift structural drift · framesmith verify / check-drift CLI for CI/pre-commit gates, no MCP client needed
Viewer	Browser gallery + detail view · phone canvases in a device frame with a safe-area overlay · quality inspector (score, issues, click-to-highlight) · design-system token panel · point-and-tell feedback (Comment mode + Feedback tab)
Open by design	MIT · plain HTML/CSS · open JSON you own in your repo · content-hash versioning (canvas_version) so approvals reference an exact design, not just a name · works with any MCP-compatible client

Viewer

Run npx -p framesmith framesmith-viewer to start the standalone browser viewer (it takes the first free port from 3001 up; pass a port to pin one). Open a web canvas to review it at multiple breakpoints and compare them side-by-side (a canvas declared desktop-app offers the narrower windows of its profile instead, 1024 and 1280 under a 1440 artboard); open any canvas to inspect its JSON, leave comments, or archive / delete it. Cards keep each artboard's proportions (between a phone held upright and 2:1; a longer page shows its top), so phone screens are portrait cards. A canvas declared mobile opens at 1:1 in a device frame instead of the breakpoint buttons, with a Safe area toggle that shades the status-bar and home-indicator insets (47 and 34 on the default iphone-390). The overlay is viewer-only: it never changes a screenshot.

Above: a canvas in the detail view with the Quality inspector on the right — the same canvas_evaluate score the agent sees, with per-category bars and the issue list; the tabs along the top switch to the Design-system and Feedback panels. The toolbar exposes breakpoint previews, Compare, Fit, JSON, a Comment toggle for point-and-tell feedback, and lifecycle actions.

Quality panel. The canvas detail view shows a read-only quality inspector on the right: the heuristic canvas_evaluate score (0–100), per-category bars, and the issue list — each cliché tell with its category · tell badge, severity, and suggestion. Issues that canvas_autofix can resolve carry an auto-fixable tag, and clicking any issue highlights its node in the live preview. Every gallery card also shows a color-coded score badge so weak canvases stand out at a glance. The score matches what your agent sees over MCP (same fast-mode evaluation, relaxed by the canvas's stored genre and applied preset) — it's computed for display only and never written back.

Above: point-and-tell in action — Comment mode is on, the clicked element is outlined, the popover's breadcrumb re-scopes the anchor, and the Feedback tab tracks open comments plus the agent's replies to resolved ones.

Feedback panel. Point-and-tell: toggle Comment in the toolbar and click any element in the preview to leave a note for the agent — a breadcrumb in the popover re-scopes the anchor from the exact element up to its card, section, or the whole page. The Feedback tab lists open comments (badge = open count) with click-to-highlight, lets you resolve or delete them, and shows the agent's resolution note as a reply once it has addressed the item. Comments persist on the canvas itself (metadata.feedback — git-diffable in bound repos) and the agent reads them over MCP via get_feedback; open feedback blocks the agent from presenting, same as open quality issues.

Design-system panel. A second inspector tab shows the canvas's effective design tokens — color swatches, type scale, spacing, and radius — resolved through the full workspace ▸ project ▸ canvas inheritance chain. Each section notes its dominant source layer, and any token resolving from a different layer is tagged (canvas / project / workspace) so you can see at a glance what a given canvas customized versus inherited.

Designs are authored through MCP tool calls from your AI assistant — in the viewer you review, comment, and manage lifecycle; you don't edit nodes. Unbound canvases persist to ~/.framesmith/canvases/ (canvases in a bound repo live in its .framesmith/ instead) so the viewer keeps showing them across sessions.

Installation

No clone or build needed — register framesmith with your MCP client via npx (requires Node 20+).

Claude Code

claude mcp add framesmith -- npx -y framesmith

Codex

Add to ~/.codex/config.toml:

[mcp_servers.framesmith]
command = "npx"
args = ["-y", "framesmith"]

Cursor

Add to ~/.cursor/mcp.json (or per-project .cursor/mcp.json):

{
  "mcpServers": {
    "framesmith": {
      "command": "npx",
      "args": ["-y", "framesmith"]
    }
  }
}

Windsurf

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "framesmith": {
      "command": "npx",
      "args": ["-y", "framesmith"]
    }
  }
}

VS Code + MCP extension

Add to .vscode/mcp.json (project-scoped) or your global MCP settings:

{
  "servers": {
    "framesmith": {
      "command": "npx",
      "args": ["-y", "framesmith"]
    }
  }
}

Any other MCP-compatible client

framesmith speaks standard stdio MCP. Point your client at npx -y framesmith using whatever config shape your client expects.

Optional: set FRAMESMITH_VIEWER_URL=http://localhost:3001 in the MCP server env to pin it to a long-lived standalone viewer process — see Running the viewer.

Build from source (for development)

git clone https://github.com/vicmaster/framesmith.git
cd framesmith
npm install
npm run build
# then point your client at: node /path/to/framesmith/dist/index.js

Tools

init

One-call onboarding — the recommended first call each session, and safe to run repeatedly (idempotent). Binds the current repo if it isn't already (canvases become checked-in JSON under .framesmith/), ensures the convention projects exist, and returns the live state you need to start working.

Param	Type	Description
dir	string?	Directory to bind / detect. Defaults to the nearest git repo root above the server working directory.
workspaceName	string?	Name for the workspace when binding fresh. Defaults to the repo folder name.
projects	string[]?	Projects to ensure exist (default: ["Foundations", "UI"]). Existing projects are never removed, so it's safe for adding feature/area projects like Onboarding.

Returns the bound workspace + project IDs (binding re-keys workspace and project IDs to repo-* — use the ones init returns; canvas IDs are kept), the on-disk layout, the workspace-layer token count, a workflow cheatsheet, the current gotchas, the framesmith://guidelines URI, and the viewer URL. If any canvas in the workspace has open point-and-tell comments, the result also carries openFeedback: { total, note } — a nudge to run get_feedback before doing anything else. It does not seed design tokens — set those at the workspace layer with workspace_set_design_system. The default Foundations project is just a canvas that visualizes the workspace tokens (which is where the design system actually lives).

canvas_create

Create a new canvas. If projectId is omitted, it lands in the built-in Untitled project of the Personal workspace.

Param	Type	Description
name	string?	Canvas name
projectId	string?	Target project. Defaults to the built-in Untitled project. See project_list.
width	number?	Artboard width in px, a positive integer (default 1440, or the device or window width for type: "mobile" / "desktop-app").
height	number?	Artboard height in px, a positive integer (default 900, or the device or window height for type: "mobile" / "desktop-app"). Each dimension defaults on its own.
type	"web" | "mobile" | "desktop-app"?	What medium the canvas is on. "desktop-app" declares an application screen, a tool you work in (an editor, an admin console, a file browser) in a browser tab or a native window: the artboard defaults to the window (1440×900), and it runs the desktop-app ruleset; a page you read and scroll stays "web". "mobile" declares a phone app screen: the artboard defaults to the device size and the root gets the device's safe-area insets as safeArea: { top, bottom }, which the renderer adds to the root's top and bottom padding. Omitted, the canvas is undeclared and judged as web. On a mobile canvas apply_structure stamps the mobile realisations (dashboard, settings, auth, onboarding, feed, detail).
device	string?	The type's profile: a phone for type: "mobile" (default "iphone-390", the only one today: 390×844, insets 47 top and 34 bottom) or a window for type: "desktop-app" (default "window-1440": 1440×900, no insets). Passing it without a type, with "web", or naming a profile from the other type's table, is an error. An explicit width/height overrides the profile's size for that side; the insets stay the profile's.

The response also carries the artboard width/height, type, typeSource ("declared" or "default"), device and safeArea for a mobile canvas, and a diversification signal for the target project: the recently-built structures (newest first) and a hint to differ on at least one taxonomy axis, so successive canvases don't converge on the same layout. It's advisory — never blocking.

canvas_list

List canvases. Excludes archived canvases by default. A row carrying openFeedback: n has open point-and-tell comments waiting — read them with get_feedback before working on that canvas.

Param	Type	Description
projectId	string?	Scope to one project
includeArchived	bool?	Include archived canvases (default false)

Returns [{ id, name, createdAt, lastModified, versionHash, projectId, archived, openFeedback?, variant?, variants? }] — openFeedback (a count) is present only when > 0; versionHash is the design-content hash canvas_version checks approvals against. variant: { of, state } is present on a state-variant row; variants: [{ state, canvasId }] rolls the designed states onto a base row (see canvas_add_variant).

canvas_add_variant

Clone a screen into a linked state variant — the empty / loading / error version of a canvas, as its own sibling canvas. The clone gets re-keyed node IDs, the same project, copied tokens/components/fonts, and carries the provenance/genre stamp (feedback and critique stay behind); it's named <base> · <state> and linked via metadata.variant = { of, state }.

Param	Type	Description
canvasId	string	The base canvas (a variant id also works — it resolves to the root base; variants never nest)
state	string	The state this variant designs — empty / loading / error recommended; free string accepted

Returns { canvasId, name, state, of, idMap } — idMap maps every base node id to its clone, so follow-up edits target the right nodes immediately. One canvas per state per base (a duplicate state errors). The viewer shows a screen and its variants as one card with state chips; canvas_list rolls designed states onto the base row.