Look up design rules (WCAG contrast, touch targets, typography) via designparser-mcp (npx)

Recipe: Look up design rules via designparser-mcp

Server: designparser-mcp v2.2.1 | Launcher: npx -y designparser-mcp | Framing: NDJSON | Auth: none | Rules: 66 bundled (offline-capable)

What it does

Serves 66 curated design rules covering color (WCAG contrast, color blindness), typography (font sizing, line height), interaction (touch targets, Fitts's law), spacing, and UX laws. Five tools let you search, drill into rules, get context-aware suggestions, and evaluate designs.

Tools inventory (5)

Startup

# Launch — NDJSON on stdio, no config needed
npx -y designparser-mcp
# Loads 66 rules from bundled rules/ directory

MCP handshake (NDJSON framing)

→ {"jsonrpc":"2.0","method":"initialize","id":1,"params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"pathfinder","version":"1.0"}}}
← {"result":{"protocolVersion":"2024-11-05","capabilities":{"tools":{},"prompts":{}},"serverInfo":{"name":"designparser-mcp","version":"2.2.1"}},"jsonrpc":"2.0","id":1}
→ {"jsonrpc":"2.0","method":"notifications/initialized"}

Example 1: Search rules by keyword

→ {"jsonrpc":"2.0","method":"tools/call","id":3,"params":{"name":"search_rules","arguments":{"query":"minimum font size readability"}}}
← 10 results including:
   - Touch Target Size (touch-target) 🔴 Critical
   - WCAG Typography (wcag-typography) 🟠 High

Latency: 7ms

Example 2: Get full rule details

→ {"jsonrpc":"2.0","method":"tools/call","id":4,"params":{"name":"get_rule","arguments":{"id":"wcag-contrast"}}}
← Full WCAG Contrast Ratio rule:
   - AA: 4.5:1 for normal text, 3:1 for large text
   - Formula: (L1 + 0.05) / (L2 + 0.05)
   - Range: 1:1 to 21:1
   - #767676 on white = 4.48:1 (fails AA for normal text)

Latency: <1ms

Example 3: Context-aware suggestions

→ {"jsonrpc":"2.0","method":"tools/call","id":5,"params":{"name":"suggest_rules_for_context","arguments":{"task":"designing a mobile checkout form with credit card input fields"}}}
← 10 relevant rules:
   - Red-Green Blindness 🔴 Critical
   - Touch Target Size 🔴 Critical
   - (+ spacing, form layout, typography rules)

Latency: 1ms

Performance

• Initialize: 5ms
• tools/list: 1ms
• search_rules: 7ms
• get_rule: <1ms
• suggestrulesfor_context: 1ms
• All responses sub-10ms (rules are bundled, no network calls)