Fastmail MCP Server

Instructions

Implementation Reference

• src/index.ts:289-296 (registration)

  Tool registration including name, description, and input schema (empty object since no parameters required) in the MCP tools list.
  { name: 'list_calendars', description: 'List all calendars', inputSchema: { type: 'object', properties: {}, }, },
• src/index.ts:822-833 (handler)

  MCP server switch-case handler that initializes the contacts/calendar client and delegates to getCalendars() method, returning JSON response.
  case 'list_calendars': { const contactsClient = initializeContactsCalendarClient(); const calendars = await contactsClient.getCalendars(); return { content: [ { type: 'text', text: JSON.stringify(calendars, null, 2), }, ], }; }
• src/contacts-calendar.ts:123-148 (handler)

  Core implementation of list_calendars: checks JMAP calendars capability/permission, constructs and sends Calendar/get JMAP request, returns list of calendars.
  async getCalendars(): Promise<any[]> { // Check permissions first const hasPermission = await this.checkCalendarsPermission(); if (!hasPermission) { throw new Error('Calendar access not available. This account may not have JMAP calendar permissions enabled. Please check your Fastmail account settings or contact support to enable calendar API access.'); } const session = await this.getSession(); const request: JmapRequest = { using: ['urn:ietf:params:jmap:core', 'urn:ietf:params:jmap:calendars'], methodCalls: [ ['Calendar/get', { accountId: session.accountId }, 'calendars'] ] }; try { const response = await this.makeRequest(request); return response.methodResponses[0][1].list; } catch (error) { // Calendar access might require special permissions throw new Error(`Calendar access not supported or requires additional permissions. This may be due to account settings or JMAP scope limitations: ${error instanceof Error ? error.message : String(error)}. Try checking account permissions or enabling calendar API access in Fastmail settings.`); } }
• src/contacts-calendar.ts:10-13 (helper)

  Helper method used by getCalendars() to verify if the JMAP calendars capability is enabled for the account.
  private async checkCalendarsPermission(): Promise<boolean> { const session = await this.getSession(); return !!session.capabilities['urn:ietf:params:jmap:calendars']; }