Gmail MCP

Instructions

Implementation Reference

• src/index.ts:1281-1294 (registration)

  Registration of the 'watch_mailbox' tool with input schema using Zod and handler function that uses the shared handleTool to call Gmail API's users.watch method for watching mailbox changes.

  server.tool("watch_mailbox",
    "Watch for changes to the user's mailbox",
    {
      topicName: z.string().describe("The name of the Cloud Pub/Sub topic to publish notifications to"),
      labelIds: z.array(z.string()).optional().describe("Label IDs to restrict notifications to"),
      labelFilterAction: z.enum(['include', 'exclude']).optional().describe("Whether to include or exclude the specified labels")
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.watch({ userId: 'me', requestBody: params })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:1283-1287 (schema)

  Input schema for the 'watch_mailbox' tool defining parameters for Pub/Sub topic and label filtering.

  {
    topicName: z.string().describe("The name of the Cloud Pub/Sub topic to publish notifications to"),
    labelIds: z.array(z.string()).optional().describe("Label IDs to restrict notifications to"),
    labelFilterAction: z.enum(['include', 'exclude']).optional().describe("Whether to include or exclude the specified labels")
  },

• src/index.ts:1288-1293 (handler)

  Handler function for 'watch_mailbox' tool that invokes the Gmail API watch endpoint via the shared handleTool utility.

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

• src/index.ts:49-65 (helper)

  Shared helper function used by all Gmail tools, including 'watch_mailbox', to handle OAuth2 authentication, 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}`
    }
  }