Gmail MCP Server

Instructions

Implementation Reference

• src/index.ts:1261-1274 (handler)

  The handler function for the 'insert_smime_info' tool, registered via server.tool(). It calls the Gmail API to insert S/MIME info for a send-as alias using handleTool wrapper. Includes inline schema definition.

  server.tool("insert_smime_info",
    "Insert (upload) the given S/MIME config for the specified send-as alias",
    {
      sendAsEmail: z.string().describe("The email address that appears in the 'From:' header"),
      encryptedKeyPassword: z.string().describe("Encrypted key password"),
      pkcs12: z.string().describe("PKCS#12 format containing a single private/public key pair and certificate chain")
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.settings.sendAs.smimeInfo.insert({ userId: 'me', sendAsEmail: params.sendAsEmail, requestBody: params })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:1264-1267 (schema)

  Input schema (Zod) for the 'insert_smime_info' tool, defining parameters sendAsEmail, encryptedKeyPassword, and pkcs12.

    sendAsEmail: z.string().describe("The email address that appears in the 'From:' header"),
    encryptedKeyPassword: z.string().describe("Encrypted key password"),
    pkcs12: z.string().describe("PKCS#12 format containing a single private/public key pair and certificate chain")
  },

• src/index.ts:1261-1274 (registration)

  Registration of the 'insert_smime_info' tool using server.tool(), including description, schema, and handler.

  server.tool("insert_smime_info",
    "Insert (upload) the given S/MIME config for the specified send-as alias",
    {
      sendAsEmail: z.string().describe("The email address that appears in the 'From:' header"),
      encryptedKeyPassword: z.string().describe("Encrypted key password"),
      pkcs12: z.string().describe("PKCS#12 format containing a single private/public key pair and certificate chain")
    },
    async (params) => {
      return handleTool(config, async (gmail: gmail_v1.Gmail) => {
        const { data } = await gmail.users.settings.sendAs.smimeInfo.insert({ userId: 'me', sendAsEmail: params.sendAsEmail, requestBody: params })
        return formatResponse(data)
      })
    }
  )

• src/index.ts:50-80 (helper)

  Shared helper function 'handleTool' used by 'insert_smime_info' and other tools for authentication, Gmail client creation, 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) {
      // Check for specific authentication errors
      if (
        error.message?.includes("invalid_grant") ||
        error.message?.includes("refresh_token") ||
        error.message?.includes("invalid_client") ||
        error.message?.includes("unauthorized_client") ||
        error.code === 401 ||
        error.code === 403
      ) {
        return formatResponse({
          error: `Authentication failed: ${error.message}. Please re-authenticate by running: npx @shinzolabs/gmail-mcp auth`,
        });
      }
  
      return formatResponse({ error: `Tool execution failed: ${error.message}` });
    }
  }