update_variants

Instructions

Implementation Reference

• src/tools/variants.ts:353-387 (handler)

  The main handler function for the 'update_variants' MCP tool. Calls the Shopify GraphQL mutation productVariantsBulkUpdate with the provided productId and variants, throws on user errors, and returns a formatted result listing updated variants.

  server.tool(
    "update_variants",
    "Update one or more existing variants in a single call. Editable fields: price, compareAtPrice (set to null to clear), SKU, barcode, taxable, inventoryPolicy (DENY blocks oversells, CONTINUE allows backorders), and optionValues (e.g. rename a size). Per-variant only; only the fields you provide are written. For inventory quantity changes use set_inventory_quantity — this tool deliberately doesn't accept quantities to keep that audit trail in one place.",
    updateVariantsSchema,
    async (args) => {
      const data = await client.graphql<{
        productVariantsBulkUpdate: {
          productVariants: VariantNode[];
          userErrors: ShopifyUserError[];
        };
      }>(VARIANTS_BULK_UPDATE_MUTATION, {
        productId: args.productId,
        variants: args.variants,
      });
      throwIfUserErrors(
        data.productVariantsBulkUpdate.userErrors,
        "productVariantsBulkUpdate",
      );
      const updated = data.productVariantsBulkUpdate.productVariants;
      return {
        content: [
          {
            type: "text" as const,
            text: [
              `Updated ${updated.length} variant(s):`,
              ...updated.map(
                (v) =>
                  `  ${v.title} ${v.price}${v.compareAtPrice ? ` (cmp ${v.compareAtPrice})` : ""}${v.sku ? ` SKU:${v.sku}` : ""} — ${v.id}`,
              ),
            ].join("\n"),
          },
        ],
      };
    },
  );

• src/tools/variants.ts:209-212 (schema)

  The Zod schema for update_variants input validation. Requires productId (string) and variants (array of variantUpdateSchema, 1-100 items).

  const updateVariantsSchema = {
    productId: z.string().describe("Product GID."),
    variants: z.array(variantUpdateSchema).min(1).max(100),
  };

• src/tools/variants.ts:182-191 (schema)

  The per-variant update schema (variantUpdateSchema). Defines editable fields: id (required), price, compareAtPrice (nullable), sku, barcode, taxable, inventoryPolicy, optionValues.

  const variantUpdateSchema = z.object({
    id: z.string().describe("Variant GID to update."),
    price: z.string().optional(),
    compareAtPrice: z.string().optional().nullable(),
    sku: z.string().optional(),
    barcode: z.string().optional(),
    taxable: z.boolean().optional(),
    inventoryPolicy: z.enum(["DENY", "CONTINUE"]).optional(),
    optionValues: z.array(optionValueInputSchema).optional(),
  });

• src/server.ts:20-64 (registration)

  Import and registration of registerVariantTools in the main server setup, which registers update_variants (along with other variant tools) on the McpServer.

  import { registerVariantTools } from "./tools/variants.js";
  import { registerFulfillmentTools } from "./tools/fulfillment.js";
  import { registerWebhookTools } from "./tools/webhooks.js";
  import { registerMetaobjectTools } from "./tools/metaobjects.js";
  import { registerAnalyticsTools } from "./tools/analytics.js";
  import { registerBridgeTools } from "./tools/bridge.js";
  
  export interface ServerConfig {
    host: string;
    port: number;
    shopifyStore: string;
    shopifyAccessToken: string;
    shopifyApiVersion?: string;
    comfyUIUrl?: string;
    comfyUIPublicUrl?: string;
    comfyUIDefaultCkpt: string;
  }
  
  interface Session {
    server: McpServer;
    transport: StreamableHTTPServerTransport;
  }
  
  function buildContext(config: ServerConfig) {
    const shopify = new ShopifyClient({
      store: config.shopifyStore,
      accessToken: config.shopifyAccessToken,
      apiVersion: config.shopifyApiVersion,
    });
    const comfyui = config.comfyUIUrl
      ? new ComfyUIClient({
          baseUrl: config.comfyUIUrl,
          publicUrl: config.comfyUIPublicUrl ?? config.comfyUIUrl,
        })
      : null;
    const buildServer = () => {
      const s = new McpServer({ name: "shopify-mcp", version: "0.1.0" });
      registerProductTools(s, shopify);
      registerOrderTools(s, shopify);
      registerInventoryTools(s, shopify);
      registerCustomerTools(s, shopify);
      registerMetafieldTools(s, shopify);
      registerDraftOrderTools(s, shopify);
      registerCollectionTools(s, shopify);
      registerVariantTools(s, shopify);

• src/tools/variants.ts:84-101 (helper)

  The GraphQL mutation string (VARIANTS_BULK_UPDATE_MUTATION) used by the update_variants handler to call productVariantsBulkUpdate.

  const VARIANTS_BULK_UPDATE_MUTATION = /* GraphQL */ `
    mutation VariantsBulkUpdate(
      $productId: ID!
      $variants: [ProductVariantsBulkInput!]!
    ) {
      productVariantsBulkUpdate(productId: $productId, variants: $variants) {
        productVariants {
          id
          title
          price
          compareAtPrice
          sku
          barcode
        }
        userErrors { field message }
      }
    }
  `;