Introduction to MCP Connecting AI Agents and Systems (Prompt Edition)

// Prompt: Template for code review instructions
server.registerPrompt(
  "code-review-prompt",
  {
    title: "code-review-prompt",
    description: "Code review instructions",
    // Definition of the arguments schema: displayed as input form in MCP clients like MCP Inspector UI and passed to the server-side function.
    argsSchema: {
      specPath: z.string().describe("Specification document path"),
      codePath: z.string().describe("Target code path"),
    },
  },
  async ({ specPath, codePath }) => {
    return {
      messages: [
        // user: Prompt body
        {
          role: "user",
          content: {
            type: "text",
            // In actual work, more detailed instructions are needed, but kept minimal here for brevity
            text: [
              "Code review instructions",
              "You are a Node.js/TypeScript backend development specialist.",
              "* Prioritized aspects: specification consistency, exception design, authorization control, transaction control, performance, maintainability, security.",
              "* Prohibitions: do not fill in specifications by guesswork. Do not make assertions without grounds.",
              "* Assign severity levels to findings as High (must address) / Medium (generally address) / Low (address if possible).",
              "* Present each finding in one line with 'Issue', 'Location', 'Suggested fix'.",
              "* Limit output to a maximum of 10 items and consolidate duplicate findings.",
              "* If improved code is needed, propose it with minimal diffs.",
              `* Specification document path: ${specPath}`,
              `* Target code path: ${codePath}`,
            ].join("\n"),
          },
        },
        // assistant: Example
        {
          role: "assistant",
          content: {
            type: "text",
            text: [
              "(Example output of code review findings)",
              "1. High: [Issue] There is an API endpoint that is not documented in the specification. [Location] The getUser function in src/api/user.ts. [Suggested fix] Remove the endpoint if it is unnecessary, or update the specification to match if it is outdated.",
              // omit
            ].join("\n"),
          },
        },
      ],
    };
  },
);

// Prompt: Template for instructions and workflows
server.registerPrompt(
  "inventory-check-workflow",
  {
    title: "inventory-check-workflow",
    description: "In-stock check workflow",
    argsSchema: {
      orderNo: z.string().describe("Order number"),
    },
  },
  async ({ orderNo }) => {
    const prompt = [
      "Inventory check workflow",
      `1. Execute get-order via tools/call (argument orderNo: "${orderNo}").`,
      "2. Execute check-attached-inventory via tools/call (arguments: orderId: the orderId from step 1 response, quantity: the total quantity from step 1 response).",
      "3. If the available field in step 2's response is true, return 'Inventory allocated'; if false, return 'Out of stock'.",
    ].join("\n");
    return { messages: [{ role: "user", content: { type: "text", text: prompt } }] };
  },
);
server.registerTool(
  "get-order",
// omit: For this example, implementations just return fixed values.
);
server.registerTool(
  "check-attached-inventory",
// omit: For this example, implementations just return fixed values.
);