Gmail MCP Server

Instructions

Implementation Reference

• src/index.ts:1144-1155 (registration)

  Registration of the 'get_send_as' MCP tool, including input schema, description, and handler function that calls the Gmail API to retrieve a specific send-as alias.

  server.tool("get_send_as",
    "Gets the specified send-as alias",
    {
      sendAsEmail: z.string().describe("The send-as alias to be retrieved")
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.settings.sendAs.get({ userId: 'me', sendAsEmail: params.sendAsEmail })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:1149-1154 (handler)

  The handler function for the 'get_send_as' tool. It uses the shared handleTool helper to authenticate, create a Gmail client, call users.settings.sendAs.get with the provided sendAsEmail, and format the response.

  async (params) => {
    return handleTool(config, async (gmail: gmail_v1.Gmail) => {
      const { data } = await gmail.users.settings.sendAs.get({ userId: 'me', sendAsEmail: params.sendAsEmail })
      return formatResponse(data)
    })
  }

• src/index.ts:1146-1148 (schema)

  Input schema for the 'get_send_as' tool, requiring a single string parameter 'sendAsEmail'.

  {
    sendAsEmail: z.string().describe("The send-as alias to be retrieved")
  },

• src/index.ts:50-66 (helper)

  Shared helper function used by all tools, including 'get_send_as', to handle OAuth2 authentication, Gmail client creation, API call execution, and error handling.

  const handleTool = async (queryConfig: Record<string, any> | undefined, apiCall: (gmail: gmail_v1.Gmail) => Promise<any>) => {
    try {
      const oauth2Client = queryConfig ? createOAuth2Client(queryConfig) : defaultOAuth2Client
      if (!oauth2Client) throw new Error('OAuth2 client could not be created, please check your credentials')
  
      const credentialsAreValid = await validateCredentials(oauth2Client)
      if (!credentialsAreValid) throw new Error('OAuth2 credentials are invalid, please re-authenticate')
  
      const gmailClient = queryConfig ? google.gmail({ version: 'v1', auth: oauth2Client }) : defaultGmailClient
      if (!gmailClient) throw new Error('Gmail client could not be created, please check your credentials')
  
      const result = await apiCall(gmailClient)
      return result
    } catch (error: any) {
      return `Tool execution failed: ${error.message}`
    }
  }

• src/index.ts:48-48 (helper)

  Helper function to format tool responses as MCP content blocks with JSON-stringified data.

  const formatResponse = (response: any) => ({ content: [{ type: "text", text: JSON.stringify(response) }] })