Guide on MCP

Setting up

Step 1: first create a typescript project

Notes

You get a json where it has: json.jsonrpc === "2.0" json.method === 'initialized'

We create a sendResponse method

response = {
        jsonrpc: '2.0',
        id: id, // json.id
        result: result,
};

the result above should have this:

{
    protocolVersion: "2025-03-26",
    capabilities: {
        tools: { listChanged: true },
    },
    serverInfo,
}

serverInfo info is json object has name and version: 1.0.0: {name: "Coffee shop Server", version: "1.0.0", }

======================

Step 2: test with mcp inspector

npx @modelcontextprotocol/inspector

ui will open. STDIO should be selected command: node arguments: location of the script ./dist/index.js

click connet and see if everything works fine:

step 3: lets add "tools/list"

const tools = [
  {
    name: "getDrinkNames",
    description: "Get the names of the drinks in the shop",
    inputSchema: { type: "object", properties: {} }
  },
  {
    name: "getDrinkInfo",
    description: "Get more info about a specific drink",
    inputSchema: { type: "object", properties: { name: { type: "string" } }, required: ["name"] }
  },
];

 if (json.method === "tools/list") {
    sendResponse(json.id, {
    tools: tools.map((tool) => ({
        name: tool.name,
        description: tool.description,
        inputSchema: tool.inputSchema,
    })),
    });
}

Try it out and see if works.

Step 4: calling a tool: We add an execute to each tool Also note the error when the tool is not found.

const tools = [
  {
    name: "getDrinkNames",
    description: "Get the names of the drinks in the shop",
    inputSchema: { type: "object", properties: {} },
    execute: async (args: any) => {
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify({ names: drinks.map((drink) => drink.name) }),
          },
        ],
      };
    },
  },
  {
    name: "getDrinkInfo",
    description: "Get more info about a specific drink",
    inputSchema: { type: "object", properties: { name: { type: "string" } }, required: ["name"] },
    execute: async (args: any) => {
      const drink = drinks.find((drink) => drink.name === args.name);
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify(drink || { error: "Drink not found" }),
          },
        ],
      };
    },
  },
];


if (json.method === "tools/call") {
        const tool = tools.find((tool) => tool.name === json.params.name);
        if (tool) {
          const toolResponse = await tool.execute(json.params.arguments);
          sendResponse(json.id, toolResponse);
        } else {
          sendResponse(json.id, {
            error: {
              code: -32602,
              message: `MCP error -32602: Tool ${json.params.name} not found`,
            },
          });
        }
      }

step 5: resources

lets create menu:

const resources = [
  {
    uri: "menu://app", /// uri should match in below
    name: "menu",
    get: async () => { // is what gets returned from this func
      return {
        contents: [
          {
            uri: "menu://app", /// uri should match in above
            text: JSON.stringify(drinks),
          },
        ],
      };
    },
  },
];

also update the initialize method code:

if (json.method === "initialize") {
    sendResponse(json.id, {
    protocolVersion: "2025-03-26",
    capabilities: {
        tools: { listChanged: true },
        resources: { listChanged: true }, // add list changed to tell if it change it should update
    },
    serverInfo,
    });
}

then you can add the method:

 if (json.method === "resources/list") {
sendResponse(json.id, {
    resources: resources.map((resource) => ({
    uri: resource.uri,
    name: resource.name,
    })),
});
}

if (json.method === "resources/read") {
    const uri = json.params.uri;
    const resource = resources.find((resource) => resource.uri === uri);
    if (resource) {
        sendResponse(json.id, await resource.get());
    } else {
        sendResponse(json.id, {
        error: { code: -32602, message: "Resource not found" },
        });
    }
}