Gmail MCP

Instructions

Implementation Reference

• src/index.ts:440-445 (handler)

  The handler function for the 'get_label' tool. It uses handleTool to manage authentication and Gmail client creation, then calls the Gmail API to retrieve the specific label by its ID, and formats the response.

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

• src/index.ts:437-439 (schema)

  Input schema for the 'get_label' tool, defining a required string parameter 'id' for the label ID.

  {
    id: z.string().describe("The ID of the label to retrieve")
  },

• src/index.ts:435-446 (registration)

  Registration of the 'get_label' tool on the MCP server, specifying name, description, input schema, and handler function.

  server.tool("get_label",
    "Get a specific label by ID",
    {
      id: z.string().describe("The ID of the label to retrieve")
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.labels.get({ userId: 'me', id: params.id })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:49-65 (helper)

  Shared helper function used by all Gmail tools, including get_label, to handle OAuth2 authentication, client creation, and error handling around API calls.

  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 to format API responses into MCP-compatible content structure for tools like get_label.

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