Gmail MCP

Instructions

Implementation Reference

• src/index.ts:1149-1166 (registration)

  Registration of the 'patch_send_as' tool, including inline schema definition and handler function that patches a send-as alias via Gmail API using gmail.users.settings.sendAs.patch
  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:1159-1165 (handler)

  The handler logic for the patch_send_as tool, which destructures params, calls handleTool with the Gmail API patch call on users.settings.sendAs, and formats the 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:1152-1157 (schema)

  Zod schema for input 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:49-65 (helper)

  Shared helper function handleTool used by patch_send_as (and other tools) to handle OAuth, create Gmail client, execute the API call, and catch 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) { return `Tool execution failed: ${error.message}` } }
• src/index.ts:47-47 (helper)

  Shared helper to format tool responses as MCP content blocks with JSON stringified data
  const formatResponse = (response: any) => ({ content: [{ type: "text", text: JSON.stringify(response) }] })