建立筆記 MCP server

本指南將帶你從頭建立完整的 MCP (Model Context Protocol) server。此 server 會管理一組 markdown 筆記，並具備以下功能：

1. 列出及讀取筆記：讓 Client 瀏覽及檢視儲存在 server 上的 markdown 檔案
2. 寫入筆記：提供建立或更新筆記的 Tool
3. 提供智慧 Prompt：產生符合情境的 Prompt，例如建立每日筆記範本或摘要現有內容

先決條件

• 已安裝 Node.js v22.13.0 或更新版本
• 支援的 Model Provider 所提供的 API 金鑰
• 現有的 Mastra 專案（請依照安裝指南設定新專案）

新增必要的相依套件與檔案

建立 MCP server 前，必須先安裝額外的相依套件，並設定基本的資料夾結構。

1. 將 @mastra/mcp 新增至專案：

   npm

   npm install @mastra/mcp@latest

   pnpm

   pnpm add @mastra/mcp@latest

   Yarn

   yarn add @mastra/mcp@latest

   Bun

   bun add @mastra/mcp@latest

2. 依照預設的安裝指南操作後，專案會包含一些與本指南無關的檔案，你可以放心移除：

   rm -rf src/mastra/agents src/mastra/workflows src/mastra/tools/weather-tool.ts

   你也應依照下列內容修改 src/mastra/index.ts 檔案：

   src/mastra/index.ts

   import { Mastra } from '@mastra/core'
   import { PinoLogger } from '@mastra/loggers'
   import { LibSQLStore } from '@mastra/libsql'
   
   export const mastra = new Mastra({
     storage: new LibSQLStore({
       id: 'mastra-storage',
       // stores telemetry, evals, ... into memory storage, if it needs to persist, change to file:../mastra.db
       url: ':memory:',
     }),
     logger: new PinoLogger({
       name: 'Mastra',
       level: 'info',
     }),
   })

3. 為 MCP server 的邏輯建立專用目錄，並建立用於存放筆記的 notes 目錄：

   mkdir notes src/mastra/mcp

   建立下列檔案：

   touch src/mastra/mcp/{server,resources,prompts}.ts

   • server.ts：包含主要 MCP server 設定
   • resources.ts：處理筆記檔案的列出與讀取作業
   • prompts.ts：包含智慧 Prompt 的邏輯

   完成後的目錄結構應如下所示：

   <your-project-name>/
   ├── notes/
   └── src/
       └── mastra/
           ├── index.ts
           ├── mcp/
           │   ├── server.ts
           │   ├── resources.ts
           │   └── prompts.ts
           └── tools/

建立 MCP server

接下來新增 MCP server！

1. 在 src/mastra/mcp/server.ts 中定義 MCP server 執行個體：

   src/mastra/mcp/server.ts

   import { MCPServer } from '@mastra/mcp'
   
   export const notes = new MCPServer({
     id: 'notes',
     name: 'Notes Server',
     version: '0.1.0',
     tools: {},
   })

   在 src/mastra/index.ts 的 Mastra 執行個體中註冊此 MCP server。notes key 是 MCP server 的公開識別碼：

   src/mastra/index.ts

   import { Mastra } from '@mastra/core'
   import { PinoLogger } from '@mastra/loggers'
   import { LibSQLStore } from '@mastra/libsql'
   import { notes } from './mcp/server'
   
   export const mastra = new Mastra({
     storage: new LibSQLStore({
       id: 'mastra-storage',
       // stores telemetry, evals, ... into memory storage, if it needs to persist, change to file:../mastra.db
       url: ':memory:',
     }),
     logger: new PinoLogger({
       name: 'Mastra',
       level: 'info',
     }),
     mcpServers: {
       notes,
     },
   })

2. Resource handler 可讓 Client 探索及讀取 server 所管理的內容。請實作 handler，以處理 notes 目錄中的 markdown 檔案。將下列內容新增至 src/mastra/mcp/resources.ts 檔案：

   src/mastra/mcp/resources.ts

   import fs from 'fs/promises'
   import path from 'path'
   import { fileURLToPath } from 'url'
   import type { MCPServerResources, Resource } from '@mastra/mcp'
   
   const __filename = fileURLToPath(import.meta.url)
   const __dirname = path.dirname(__filename)
   const NOTES_DIR = path.resolve(__dirname, '../../notes') // relative to the default output directory
   
   const listNoteFiles = async (): Promise<Resource[]> => {
     try {
       await fs.mkdir(NOTES_DIR, { recursive: true })
       const files = await fs.readdir(NOTES_DIR)
       return files
         .filter(file => file.endsWith('.md'))
         .map(file => {
           const title = file.replace('.md', '')
           return {
             uri: `notes://${title}`,
             name: title,
             description: `A note about ${title}`,
             mime_type: 'text/markdown',
           }
         })
     } catch (error) {
       console.error('Error listing note resources:', error)
       return []
     }
   }
   
   const readNoteFile = async (uri: string): Promise<string | null> => {
     const title = uri.replace('notes://', '')
     const notePath = path.join(NOTES_DIR, `${title}.md`)
     try {
       return await fs.readFile(notePath, 'utf-8')
     } catch (error) {
       if ((error as NodeJS.ErrnoException).code !== 'ENOENT') {
         console.error(`Error reading resource ${uri}:`, error)
       }
       return null
     }
   }
   
   export const resourceHandlers: MCPServerResources = {
     listResources: listNoteFiles,
     getResourceContent: async ({ uri }: { uri: string }) => {
       const content = await readNoteFile(uri)
       if (content === null) return { text: '' }
       return { text: content }
     },
   }

   在 src/mastra/mcp/server.ts 中註冊這些 Resource handler：

   src/mastra/mcp/server.ts

   import { MCPServer } from '@mastra/mcp'
   import { resourceHandlers } from './resources'
   
   export const notes = new MCPServer({
     id: 'notes',
     name: 'Notes Server',
     version: '0.1.0',
     tools: {},
     resources: resourceHandlers,
   })

3. Tool 是 server 可以執行的動作。接著建立 write Tool。 首先，在 src/mastra/tools/write-note.ts 中定義 Tool：

   src/mastra/tools/write-note.ts

   import { createTool } from '@mastra/core/tools'
   import { z } from 'zod'
   import { fileURLToPath } from 'url'
   import path from 'node:path'
   import fs from 'fs/promises'
   
   const __filename = fileURLToPath(import.meta.url)
   const __dirname = path.dirname(__filename)
   const NOTES_DIR = path.resolve(__dirname, '../../../notes')
   
   export const writeNoteTool = createTool({
     id: 'write',
     description: 'Write a new note or overwrite an existing one.',
     inputSchema: z.object({
       title: z.string().nonempty().describe('The title of the note. This will be the filename.'),
       content: z.string().nonempty().describe('The markdown content of the note.'),
     }),
     outputSchema: z.string().nonempty(),
     execute: async inputData => {
       try {
         const { title, content } = inputData
         const filePath = path.join(NOTES_DIR, `${title}.md`)
         await fs.mkdir(NOTES_DIR, { recursive: true })
         await fs.writeFile(filePath, content, 'utf-8')
         return `Successfully wrote to note \"${title}\".`
       } catch (error: any) {
         return `Error writing note: ${error.message}`
       }
     },
   })

   在 src/mastra/mcp/server.ts 中註冊此 Tool：

   src/mastra/mcp/server.ts

   import { MCPServer } from '@mastra/mcp'
   import { resourceHandlers } from './resources'
   import { writeNoteTool } from '../tools/write-note'
   
   export const notes = new MCPServer({
     id: 'notes',
     name: 'Notes Server',
     version: '0.1.0',
     resources: resourceHandlers,
     tools: {
       write: writeNoteTool,
     },
   })

4. Prompt handler 會為 Client 提供可直接使用的 Prompt。你將新增以下三種：

   • 每日筆記
   • 摘要筆記
   • 腦力激盪

   此功能需要安裝幾個 markdown 剖析函式庫：

   npm install unified remark-parse gray-matter @types/unist

   在 src/mastra/mcp/prompts.ts 中實作 Prompt：

   src/mastra/mcp/prompts.ts

   import type { MCPServerPrompts } from '@mastra/mcp'
   import { unified } from 'unified'
   import remarkParse from 'remark-parse'
   import matter from 'gray-matter'
   import type { Node } from 'unist'
   
   const prompts = [
     {
       name: 'new_daily_note',
       description: 'Create a new daily note.',
       version: '1.0.0',
     },
     {
       name: 'summarize_note',
       description: 'Give me a TL;DR of the note.',
       version: '1.0.0',
     },
     {
       name: 'brainstorm_ideas',
       description: 'Brainstorm new ideas based on a note.',
       version: '1.0.0',
     },
   ]
   
   function stringifyNode(node: Node): string {
     if ('value' in node && typeof node.value === 'string') return node.value
     if ('children' in node && Array.isArray(node.children))
       return node.children.map(stringifyNode).join('')
     return ''
   }
   
   export async function analyzeMarkdown(md: string) {
     const { content } = matter(md)
     const tree = unified().use(remarkParse).parse(content)
     const headings: string[] = []
     const wordCounts: Record<string, number> = {}
     let currentHeading = 'untitled'
     wordCounts[currentHeading] = 0
     tree.children.forEach(node => {
       if (node.type === 'heading' && node.depth === 2) {
         currentHeading = stringifyNode(node)
         headings.push(currentHeading)
         wordCounts[currentHeading] = 0
       } else {
         const textContent = stringifyNode(node)
         if (textContent.trim()) {
           wordCounts[currentHeading] =
             (wordCounts[currentHeading] || 0) + textContent.split(/\\s+/).length
         }
       }
     })
     return { headings, wordCounts }
   }
   
   const getPromptMessages: MCPServerPrompts['getPromptMessages'] = async ({ name, args }) => {
     switch (name) {
       case 'new_daily_note':
         const today = new Date().toISOString().split('T')[0]
         return [
           {
             role: 'user',
             content: {
               type: 'text',
               text: `Create a new note titled \"${today}\" with sections: \"## Tasks\", \"## Meetings\", \"## Notes\".`,
             },
           },
         ]
       case 'summarize_note':
         if (!args?.noteContent) throw new Error('No content provided')
         const metaSum = await analyzeMarkdown(args.noteContent as string)
         return [
           {
             role: 'user',
             content: {
               type: 'text',
               text: `Summarize each section in ≤ 3 bullets.\\n\\n### Outline\\n${metaSum.headings.map(h => `- ${h} (${metaSum.wordCounts[h] || 0} words)`).join('\\n')}`.trim(),
             },
           },
         ]
       case 'brainstorm_ideas':
         if (!args?.noteContent) throw new Error('No content provided')
         const metaBrain = await analyzeMarkdown(args.noteContent as string)
         return [
           {
             role: 'user',
             content: {
               type: 'text',
               text: `Brainstorm 3 ideas for underdeveloped sections below ${args?.topic ? `on ${args.topic}` : '.'}\\n\\nUnderdeveloped sections:\\n${metaBrain.headings.length ? metaBrain.headings.map(h => `- ${h}`).join('\\n') : '- (none, pick any)'}`,
             },
           },
         ]
       default:
         throw new Error(`Prompt \"${name}\" not found`)
     }
   }
   
   export const promptHandlers: MCPServerPrompts = {
     listPrompts: async () => prompts,
     getPromptMessages,
   }

   在 src/mastra/mcp/server.ts 中註冊這些 Prompt handler：

   src/mastra/mcp/server.ts

   import { MCPServer } from '@mastra/mcp'
   import { resourceHandlers } from './resources'
   import { writeNoteTool } from '../tools/write-note'
   import { promptHandlers } from './prompts'
   
   export const notes = new MCPServer({
     id: 'notes',
     name: 'Notes Server',
     version: '0.1.0',
     resources: resourceHandlers,
     prompts: promptHandlers,
     tools: {
       write: writeNoteTool,
     },
   })

執行 server

太好了，你已經完成第一個 MCP server！現在可以啟動 Mastra 開發伺服器並開啟 Studio，試用這個 server：

npm run dev

在瀏覽器中開啟 http://localhost:4111。在左側邊欄選取 MCP Servers，再選取 notes MCP server。

畫面現在會顯示如何將 MCP server 新增至 IDE 的說明。你可以搭配任何 MCP Client 使用此 MCP server。在右側的 Available Tools 下方，也可以選取 write Tool。

在 write Tool 中，輸入 test 作為名稱，並以 this is a test 作為 markdown 內容來試用。選取 Submit 後，notes 中就會新增一個 test.md 檔案。