Gmail MCP

Instructions

Implementation Reference

• src/index.ts:1214-1226 (registration)

  Registration of the 'get_smime_info' tool, including input schema and inline handler function. The handler uses the Gmail API to retrieve specified S/MIME configuration for a send-as alias.

  server.tool("get_smime_info",
    "Gets the specified S/MIME config for the specified send-as alias",
    {
      sendAsEmail: z.string().describe("The email address that appears in the 'From:' header"),
      id: z.string().describe("The immutable ID for the S/MIME config")
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.settings.sendAs.smimeInfo.get({ userId: 'me', sendAsEmail: params.sendAsEmail, id: params.id })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:1220-1226 (handler)

  Handler function for 'get_smime_info' tool that authenticates via handleTool, calls Gmail API gmail.users.settings.sendAs.smimeInfo.get, and formats the response.

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

• src/index.ts:1216-1219 (schema)

  Input schema for 'get_smime_info' tool using Zod: requires sendAsEmail and id.

  {
    sendAsEmail: z.string().describe("The email address that appears in the 'From:' header"),
    id: z.string().describe("The immutable ID for the S/MIME config")
  },

• src/index.ts:49-65 (helper)

  Shared helper function handleTool used by all Gmail API tools, including get_smime_info, for OAuth authentication and API 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:47-47 (helper)

  Helper function to format API responses into MCP content structure, used by get_smime_info handler.

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