PostCartsIdLineItems
Add a product variant to a cart using a specific line item. Simplify cart management and ensure accurate product selection with this Medusa MCP Server tool.
Instructions
Add a product variant as a line item in the cart.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| fields | No | ||
| id | No |
Implementation Reference
- src/services/medusa-store.ts:83-127 (handler)Generic handler for all Medusa Store API tools, including 'PostCartsIdLineItems'. Parses input into query/body parameters and invokes the Medusa JS SDK client.fetch for the corresponding OpenAPI path.handler: async ( input: InferToolHandlerInput<any, ZodTypeAny> ): Promise<any> => { const query = new URLSearchParams(input); const body = Object.entries(input).reduce( (acc, [key, value]) => { if ( parameters.find( (p) => p.name === key && p.in === "body" ) ) { acc[key] = value; } return acc; }, {} as Record<string, any> ); if (method === "get") { console.error( `Fetching ${refPath} with GET ${query.toString()}` ); const response = await this.sdk.client.fetch(refPath, { method: method, headers: { "Content-Type": "application/json", "Accept": "application/json", "Authorization": `Bearer ${process.env.PUBLISHABLE_KEY}` }, query: query }); return response; } else { const response = await this.sdk.client.fetch(refPath, { method: method, headers: { "Content-Type": "application/json", "Accept": "application/json", "Authorization": `Bearer ${process.env.PUBLISHABLE_KEY}` }, body: JSON.stringify(body) }); return response; } } };
- src/services/medusa-store.ts:54-82 (schema)Dynamically generates the Zod input schema for the tool based on OpenAPI parameters from store.json, excluding headers. Supports string, number, boolean, array, object types.inputSchema: { ...parameters .filter((p) => p.in != "header") .reduce((acc, param) => { switch (param.schema.type) { case "string": acc[param.name] = z.string().optional(); break; case "number": acc[param.name] = z.number().optional(); break; case "boolean": acc[param.name] = z.boolean().optional(); break; case "array": acc[param.name] = z .array(z.string()) .optional(); break; case "object": acc[param.name] = z.object({}).optional(); break; default: acc[param.name] = z.string().optional(); } return acc; }, {} as any) },
- src/index.ts:35-42 (registration)Registers all dynamically generated tools (including PostCartsIdLineItems) to the MCP server using server.tool().tools.forEach((tool) => { server.tool( tool.name, tool.description, tool.inputSchema, tool.handler ); });
- src/services/medusa-store.ts:131-137 (registration)Defines all store tools by iterating over OpenAPI paths in store.json and wrapping each into a tool using wrapPath, which sets name from operationId.defineTools(store = storeJson): any[] { const paths = Object.entries(store.paths) as [string, SdkRequestType][]; const tools = paths.map(([path, refFunction]) => this.wrapPath(path, refFunction) ); return tools; }
- src/utils/define-tools.ts:16-60 (helper)Utility function that wraps tool definitions, providing error handling and formatting the output as MCP CallToolResult content.export const defineTool = ( cb: (zod: typeof z) => ToolDefinition<any, ZodAny, any> ) => { const tool = cb(z); const wrappedHandler = async ( input: InferToolHandlerInput<Zod.ZodAny, Zod.ZodAny>, _: RequestHandlerExtra ): Promise<{ content: CallToolResult["content"]; isError?: boolean; statusCode?: number; }> => { try { const result = await tool.handler(input); return { content: [ { type: "text", text: JSON.stringify(result, null, 2) } ] }; } catch (error) { return { content: [ { type: "text", text: `Error: ${ error instanceof Error ? error.message : String(error) }` } ], isError: true }; } }; return { ...tool, handler: wrappedHandler }; };