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) }] })