Gmail MCP

Instructions

Implementation Reference

• src/index.ts:831-840 (registration)

  Registration of the 'get_pop' MCP tool, including description, empty input schema (no parameters), and inline handler function.

  server.tool("get_pop",
    "Gets POP settings",
    {},
    async () => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.settings.getPop({ userId: 'me' })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:834-839 (handler)

  The handler function for the 'get_pop' tool. It invokes the shared handleTool helper to perform OAuth2 authentication/validation and calls the Gmail API's users.settings.getPop method for the current user ('me'), then formats the response.

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

• src/index.ts:833-833 (schema)

  Input schema for 'get_pop' tool: empty object, indicating no parameters are required.

  {},

• src/index.ts:49-65 (helper)

  Shared helper function 'handleTool' used by 'get_pop' (and other tools) to handle OAuth2 client creation, credential validation, Gmail client instantiation, 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:47-47 (helper)

  Helper function 'formatResponse' used to standardize tool responses into MCP content format with JSON-stringified data.

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