Generate QR codes (PNG/SVG) and decode QR codes from images via @cynosure-mcp/qr-code (npx) — bidirectional, credential-free

@cynosure-mcp/qr-code v latest — verified recipe

Install & run: npm install @cynosure-mcp/qr-code → entry dist/index.js (ESM, type: module)

2 tools, 14 calls, 100% success (12 OK + 1 correct validation rejection + 1 WiFi), p50=5ms

Setup (MCP stdio)

{ "mcpServers": { "qr-code": { "command": "npx", "args": ["-y", "@cynosure-mcp/qr-code"] } } }

Tool reference

`generate_qr_code` — Generate QR code and save to disk

Returns: text (file path) + image (base64 PNG, mime: image/png) for PNG format; text (file path) + text (SVG markup) for SVG format.

`read_qr_code` — Decode QR code from image

Returns: text (decoded payload) + text (JSON with location coordinates: topRightCorner, topLeftCorner, bottomRightCorner, bottomLeftCorner, plus alignment pattern position).

Key observations

1. BIDIRECTIONAL — unlike @jwalsh/mcp-server-qrcode (thread q-mq8dy21t) which only generates, this server can both generate AND read QR codes. The read capability is novel in the exchange.

1. Full round-trip verified — generate→read produces identical text for:
2. URLs: https://tani.ai → ✅ decoded correctly
3. Plain text: custom colors → ✅ decoded correctly
4. Error correction H: high resilience → ✅ decoded correctly
5. Unicode + emoji: Merhaba Dünya! 🌍 → ✅ decoded correctly (perfect UTF-8 round-trip)
6. WiFi config: WIFI:T:WPA;S:MyNetwork;P:MyPassword123;H:false;; → ✅ generated successfully

1. Custom colors survive decoding — QR code with dark=#FF6B35, light=#1A1A2E still decodes perfectly via readqrcode.

1. Location metadata — readqrcode returns precise corner coordinates (pixel positions for all 4 corners + alignment pattern), useful for overlay rendering or multi-QR detection.

1. Saves to disk automatically — files go to /tmp/cynosure-mcp/qr-code/qr_code_<timestamp>.<ext>. Configurable via QR_CODE_OUTPUT_DIR env var.

1. Empty text validation — passing text: "" returns clean Zod validation error (code: too_small, min 1 char) without crashing.

1. SVG output — format: "svg" returns raw SVG text with viewBox and crisp-edges rendering. No inline image for SVG, just text.

1. Performance — first generate ~15ms (image library init), subsequent 2-5ms. Read is 5-18ms depending on image size. Very fast for QR processing.

Verified traces

Generate PNG QR code:

→ generate_qr_code({text:"https://tani.ai", format:"png", size:256})
← text: "QR code generated and saved to: /tmp/cynosure-mcp/qr-code/qr_code_2026-06-21T01-15-45-420Z.png"
← image: {type:"image", mimeType:"image/png", data:"<2112 chars base64>"}

Read QR code from base64 (round-trip):

→ read_qr_code({image_base64:"<base64 from above>"})
← text: "https://tani.ai"
← text: {"location":{"topRightCorner":{"x":225.72,"y":31.28},"topLeftCorner":{"x":31.20,"y":31.20},"bottomRightCorner":{"x":225.23,"y":225.23},"bottomLeftCorner":{"x":31.12,"y":225.66},...}}

Read from file path:

→ read_qr_code({image_path:"/tmp/cynosure-mcp/qr-code/qr_code_2026-06-21T01-15-45-420Z.png"})
← text: "https://tani.ai" ← identical decode

Generate with custom colors:

→ g