Shopify Functions

What it does

When your agent uses it

• Creating custom discount rules
• Payment customizations
• Delivery options
• Cart transformations that run server-side at checkout

Example prompts

• “shopify functions”
• “shopify discounts”
• “shopify wasm”
• “/shopify-functions”

Requirements

• Node.js
• Compatibility (from SKILL.md): Designed for Claude Code
• Pre-approved tools (allowed-tools): Read, Write, Edit, Bash(npm:*), Grep

Workflow steps

4 steps, taken from the step headings in SKILL.md.

1. 1Configure the Function Extension
2. 2Define the Input Query
3. 3Implement the Function
4. 4Test and Deploy

What it can do on your machine

Read from SKILL.md and the folder at commit cfae287. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Write
  • Edit
  • Bash(npm:*)
  • Grep

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • shopify
  • npm

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • shopify.dev

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Designed for Claude Code

  From compatibility in the SKILL.md frontmatter.

Context cost

Shopify Functions loads about 1.3k tokens when it runs, and up to ~3.8k if it reads all its reference files. Until then it costs about 99 tokens; SKILL.md has 313 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~99

When it runs · the whole SKILL.md, loaded when a task matches

~1.3k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~3.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from jeremylongshore/tons-of-skills-marketplace at commit cfae287, republished under its MIT licence (© jeremylongshore). 313 words, ~1,306 tokens.

name

shopify-functions

description

Build Shopify Functions for custom discount, payment, and delivery logic in a WASM sandbox. Use when creating custom discount rules, payment customizations, delivery options, or cart transformations that run server-side at checkout. Trigger with phrases like "shopify functions", "shopify discounts", "shopify wasm", "custom discount function", "shopify checkout customization".

allowed-tools

Read, Write, Edit, Bash(npm:*), Grep

compatibility

Designed for Claude Code

version

2.7.0

license

MIT

author

Jeremy Longshore <jeremy@intentsolutions.io>

tags

saas, ecommerce, shopify

# extensions/product-discount/shopify.extension.toml
api_version = "2025-01"
type = "product_discounts"

[[targeting]]
target = "purchase.product-discount.run"
input_query = "extensions/product-discount/input.graphql"
export = "run"

# extensions/product-discount/input.graphql
query Input {
  cart {
    lines {
      quantity
      merchandise {
        ... on ProductVariant {
          id
          product { hasAnyTag(tags: ["VIP-DISCOUNT"]) }
        }
      }
    }
  }
  discountNode {
    metafield(namespace: "$app:discount-config", key: "percentage") { value }
  }
}

// extensions/product-discount/src/run.ts
import type { Input, FunctionRunResult } from "../generated/api";

export function run(input: Input): FunctionRunResult {
  const percentage = parseFloat(input.discountNode?.metafield?.value ?? "0");
  if (percentage === 0) return { discounts: [], discountApplicationStrategy: "FIRST" };

  const targets = input.cart.lines
    .filter((line) => line.merchandise.product.hasAnyTag)
    .map((line) => ({ productVariant: { id: line.merchandise.id } }));

  return {
    discounts: [{
      targets,
      value: { percentage: { value: percentage.toString() } },
      message: `${percentage}% VIP Discount`,
    }],
    discountApplicationStrategy: "FIRST",
  };
}

shopify app function typegen          # Generate types from input query
shopify app function build            # Build to WASM
shopify app function run --input test-input.json  # Test locally
shopify app deploy                    # Deploy with app

© jeremylongshore, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files (references) in skills/.curated/shopify-functions of jeremylongshore/tons-of-skills-marketplace.

• SKILL.md
• references/function-types.md
• references/input-output-schemas.md
• references/wasm-constraints.md

Open the folder on GitHubat commit cfae287