Medusa MCP Server

Instructions

Implementation Reference

• src/index.ts:35-42 (registration)

  Registers all tools, including PostCartsIdPromotions, on the MCP server by calling server.tool for each tool from services.
  tools.forEach((tool) => { server.tool( tool.name, tool.description, tool.inputSchema, tool.handler ); });
• src/index.ts:14-17 (registration)

  Calls defineTools on MedusaStoreService to get the list of store tools, including PostCartsIdPromotions.
  tools = [ ...medusaStoreService.defineTools(), ...medusaAdminService.defineTools() ];
• src/services/medusa-store.ts:131-137 (helper)

  Generates all store API tools by iterating over OpenAPI spec paths and wrapping each with wrapPath, including the one for PostCartsIdPromotions.
  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/services/medusa-store.ts:83-126 (handler)

  Handler logic for the PostCartsIdPromotions tool (and all store POST tools): constructs query/body from input, calls Medusa SDK fetch with POST method to the specific refPath for carts/{id}/promotions.
  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 input schema for PostCartsIdPromotions from the OpenAPI parameters of the /carts/{id}/promotions endpoint.
  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) },