Gmail MCP Server

Instructions

Implementation Reference

• src/index.ts:1206-1217 (registration)

  Registration of the 'verify_send_as' tool, including inline schema and handler. The handler uses 'handleTool' to validate credentials and call Gmail API's users.settings.sendAs.verify to send a verification email to the specified send-as alias.

  server.tool("verify_send_as",
    "Sends a verification email to the specified send-as alias",
    {
      sendAsEmail: z.string().describe("The send-as alias to be verified")
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.settings.sendAs.verify({ userId: 'me', sendAsEmail: params.sendAsEmail })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:1211-1216 (handler)

  Handler function for 'verify_send_as' tool. It invokes the shared 'handleTool' utility which handles OAuth validation and executes the Gmail API call to verify the send-as alias by sending an email.

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

• src/index.ts:1207-1209 (schema)

  Input schema for 'verify_send_as' tool using Zod: requires 'sendAsEmail' as a string.

  "Sends a verification email to the specified send-as alias",
  {
    sendAsEmail: z.string().describe("The send-as alias to be verified")

• src/index.ts:50-66 (helper)

  Shared 'handleTool' helper used by all Gmail tools, including 'verify_send_as'. It creates/validates OAuth2 client, initializes Gmail client, executes the provided API callback, and handles errors.

  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:48-49 (helper)

  'formatResponse' helper used by 'verify_send_as' handler to format the API response as MCP content.

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