Gmail MCP Server

Instructions

Implementation Reference

• src/index.ts:1182-1199 (registration)

  Registration of the 'patch_send_as' tool, including schema definition and inline handler function that updates a send-as alias via Gmail API patch call.
  server.tool("patch_send_as", "Patches the specified send-as alias", { sendAsEmail: z.string().describe("The send-as alias to be updated"), displayName: z.string().optional().describe("A name that appears in the 'From:' header"), replyToAddress: z.string().optional().describe("An optional email address that is included in a 'Reply-To:' header"), signature: z.string().optional().describe("An optional HTML signature"), isPrimary: z.boolean().optional().describe("Whether this address is the primary address"), treatAsAlias: z.boolean().optional().describe("Whether Gmail should treat this address as an alias") }, async (params) => { const { sendAsEmail, ...patchData } = params return handleTool(config, async (gmail: gmail_v1.Gmail) => { const { data } = await gmail.users.settings.sendAs.patch({ userId: 'me', sendAsEmail, requestBody: patchData }) return formatResponse(data) }) } )
• src/index.ts:1192-1198 (handler)

  The core handler logic for 'patch_send_as': destructures params, calls Gmail API's users.settings.sendAs.patch with sendAsEmail and patchData, formats response.
  async (params) => { const { sendAsEmail, ...patchData } = params return handleTool(config, async (gmail: gmail_v1.Gmail) => { const { data } = await gmail.users.settings.sendAs.patch({ userId: 'me', sendAsEmail, requestBody: patchData }) return formatResponse(data) }) }
• src/index.ts:1185-1191 (schema)

  Input schema using Zod for validating parameters to the 'patch_send_as' tool.
  sendAsEmail: z.string().describe("The send-as alias to be updated"), displayName: z.string().optional().describe("A name that appears in the 'From:' header"), replyToAddress: z.string().optional().describe("An optional email address that is included in a 'Reply-To:' header"), signature: z.string().optional().describe("An optional HTML signature"), isPrimary: z.boolean().optional().describe("Whether this address is the primary address"), treatAsAlias: z.boolean().optional().describe("Whether Gmail should treat this address as an alias") },
• src/index.ts:50-80 (helper)

  Shared helper function 'handleTool' used by 'patch_send_as' and other tools to handle OAuth2 authentication, create Gmail client, execute API call, and handle errors.
  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}` }); } }