Gmail MCP Server

Instructions

Implementation Reference

• src/index.ts:721-736 (handler)

  The handler function for the 'get_thread' tool. It uses handleTool to authenticate and call Gmail API to get the thread by ID with full format, processes each message's payload using processMessagePart, and formats the response.
  async (params) => { return handleTool(config, async (gmail: gmail_v1.Gmail) => { const { data } = await gmail.users.threads.get({ userId: 'me', id: params.id, format: 'full' }) if (data.messages) { data.messages = data.messages.map(message => { if (message.payload) { message.payload = processMessagePart(message.payload, params.includeBodyHtml) } return message }) } return formatResponse(data) }) }
• src/index.ts:717-720 (schema)

  Input schema for 'get_thread' tool defining parameters: id (string, required), includeBodyHtml (boolean, optional).
  { id: z.string().describe("The ID of the thread to retrieve"), includeBodyHtml: z.boolean().optional().describe("Whether to include the parsed HTML in the return for each body, excluded by default because they can be excessively large") },
• src/index.ts:715-737 (registration)

  Registration of the 'get_thread' tool on the MCP server, including description, input schema, and handler function.
  server.tool("get_thread", "Get a specific thread by ID", { id: z.string().describe("The ID of the thread to retrieve"), includeBodyHtml: z.boolean().optional().describe("Whether to include the parsed HTML in the return for each body, excluded by default because they can be excessively large") }, async (params) => { return handleTool(config, async (gmail: gmail_v1.Gmail) => { const { data } = await gmail.users.threads.get({ userId: 'me', id: params.id, format: 'full' }) if (data.messages) { data.messages = data.messages.map(message => { if (message.payload) { message.payload = processMessagePart(message.payload, params.includeBodyHtml) } return message }) } return formatResponse(data) }) } )
• src/index.ts:50-66 (helper)

  Shared helper function used by 'get_thread' (and other tools) to handle OAuth2 client creation, credential validation, Gmail client setup, and API call execution with 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:80-94 (helper)

  Helper function to recursively process message parts: decodes body data for non-HTML or if includeBodyHtml, recurses on parts, filters headers to specific list. Used in 'get_thread' to process thread messages.
  const processMessagePart = (messagePart: MessagePart, includeBodyHtml = false): MessagePart => { if ((messagePart.mimeType !== 'text/html' || includeBodyHtml) && messagePart.body) { messagePart.body = decodedBody(messagePart.body) } if (messagePart.parts) { messagePart.parts = messagePart.parts.map(part => processMessagePart(part, includeBodyHtml)) } if (messagePart.headers) { messagePart.headers = messagePart.headers.filter(header => RESPONSE_HEADERS_LIST.includes(header.name || '')) } return messagePart }