Gmail MCP Server

Instructions

Implementation Reference

• src/index.ts:1157-1166 (registration)

  Registration of the 'list_send_as' MCP tool, including schema (empty, no params) and inline handler that lists send-as aliases using Gmail users.settings.sendAs.list API.

  server.tool("list_send_as",
    "Lists the send-as aliases for the specified account",
    {},
    async () => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.settings.sendAs.list({ userId: 'me' })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:1160-1165 (handler)

  The handler function for 'list_send_as' tool: invokes handleTool to authenticate and call Gmail API's users.settings.sendAs.list with userId 'me', formats response.

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

• src/index.ts:50-66 (helper)

  Shared helper function used by all Gmail tools, including list_send_as, to handle OAuth2 authentication, credential validation, Gmail client creation, and API call execution.

  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)

  Helper to format API responses as MCP content blocks with JSON stringified text.

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