Packrift MCP Server

Production MCP (Model Context Protocol) server for Packrift, a Shopify packaging-supplies store. Lets AI agents search the catalog, get live pricing and inventory, recommend a box for an item, estimate shipping, and produce checkout URLs.

• Stack: Cloudflare Workers, TypeScript (strict), Hono, Zod, Streamable HTTP transport
• Backing: Shopify Admin GraphQL API (2025-04), store packrift.myshopify.com
• Endpoint: POST /mcp, GET /mcp (SSE), GET / (health), GET /.well-known/mcp/server-card.json

Tools

Tool	Purpose
search_products(query, limit?)	Keyword search across the catalog. Cached 5 min in KV.
get_product(handle)	Full product detail incl. variants, dimensions metafield, weight.
get_pricing(variant_ids[], quantity?)	Live unit price + line total. Never cached.
check_inventory(variant_ids[])	Live inventory count. Never cached.
recommend_packaging(dims, weight, use_case)	Up to 5 ranked variant suggestions with 0.5–2 in padding.
get_shipping_estimate(zip, country, items[])	Carrier rates via Shopify draftOrderCalculate.
create_cart_url(items[], discount_code?, ref?)	Builds packrift.com/cart/...?ref=mcp[&discount=...].

Local development

Install Node 24+ and the deps:

cd ~/Downloads/packrift-mcp-server
npm install

Local secrets — already created at .dev.vars (gitignored):

SHOPIFY_PACKRIFT_TOKEN=shpat_...

Run the server:

npx wrangler dev --port 8787 --local

Smoke-test the MCP endpoint with curl:

# initialize
curl -s -X POST http://127.0.0.1:8787/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"curl","version":"1"}}}'

# list tools
curl -s -X POST http://127.0.0.1:8787/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/list"}'

# search
curl -s -X POST http://127.0.0.1:8787/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"search_products","arguments":{"query":"poly mailer","limit":3}}}'

Type-check:

npx tsc --noEmit

Deployment

The Cloudflare account is being created in a separate process. Once it's ready and wrangler is logged in (wrangler login), run these in order:

cd ~/Downloads/packrift-mcp-server

# 1. Create the KV namespace and copy the printed id into wrangler.toml
#    (replace both `id` and `preview_id` with the same value).
npx wrangler kv namespace create CATALOG_CACHE

# 2. Set the Shopify Admin token as a secret (paste shpat_... when prompted).
npx wrangler secret put SHOPIFY_PACKRIFT_TOKEN

# 3. Deploy. Initial deploy puts the worker on
#    https://packrift-mcp.<account>.workers.dev
npx wrangler deploy

# 4. (Once mcp.packrift.com is CNAME'd to the worker) uncomment the [[routes]]
#    block in wrangler.toml and redeploy.
npx wrangler deploy

After deploy, the MCP endpoint is https://packrift-mcp.<account>.workers.dev/mcp (and later https://mcp.packrift.com/mcp). The server card lives at /.well-known/mcp/server-card.json.

Design notes / caveats

• cartCreate is a Storefront API mutation, not Admin. The brief asked for cartCreate + cartBuyerIdentityUpdate for shipping rates, but those don't exist on the Admin GraphQL API this server uses. The supported Admin path is draftOrderCalculate, which is what get_shipping_estimate uses. It returns the same carrier-rate data without creating a real order.
• Dimensions parsing. Packrift product dimensions live in custom.specN_value metafields where the matching custom.specN_name says "Dimensions" or "Size". Format is human-readable (12 1/8" L x 11 5/8" W x 2 5/8" H). src/dimensions.ts parses mixed fractions and falls back to scanning the title.
• Recommend collections. The brief mentioned mailer-boxes collection — that handle does not exist on the live store. We use mailers-envelopes, boxes-mailers, corrugated-boxes, bubble-wrap-foam, cushioning, and ecommerce-fulfillment (verified via collections query 2026-04-29).
• Use case mapping is in src/tools/recommend_packaging.ts (COLLECTIONS_BY_USE_CASE).
• Shipping rate handle in the response is a long opaque JWT-style string — that's how Shopify returns rate handles; pass it through to subsequent calls if needed.
• Errors: tool exceptions are returned as { content: [...], isError: true } per the MCP spec, not as JSON-RPC -3260x errors. Protocol-level errors (unknown tool, bad JSON) do return JSON-RPC errors.

File map

src/
  index.ts                       Hono app + MCP JSON-RPC dispatcher
  shopify.ts                     Admin GraphQL client + id helpers
  dimensions.ts                  Spec-string -> structured dimensions
  server-card.ts                 /.well-known card
  tools/
    search_products.ts
    get_product.ts
    get_pricing.ts
    check_inventory.ts
    recommend_packaging.ts
    get_shipping_estimate.ts
    create_cart_url.ts
wrangler.toml                    Worker config (KV binding, vars, route)
package.json
tsconfig.json
.dev.vars                        Local-only secrets (gitignored)