Fastmail MCP Server

Instructions

Implementation Reference

• src/index.ts:662-672 (handler)

  MCP tool handler for 'list_mailboxes': initializes JmapClient, calls getMailboxes(), and returns JSON stringified list of mailboxes.
  case 'list_mailboxes': { const mailboxes = await client.getMailboxes(); return { content: [ { type: 'text', text: JSON.stringify(mailboxes, null, 2), }, ], }; }
• src/index.ts:138-145 (schema)

  Tool schema definition including name, description, and empty input schema (no parameters required). Returned in ListTools response.
  { name: 'list_mailboxes', description: 'List all mailboxes in the Fastmail account', inputSchema: { type: 'object', properties: {}, }, },
• src/jmap-client.ts:82-94 (helper)

  JmapClient helper method that sends JMAP Mailbox/get request to retrieve all mailboxes and returns the list.
  async getMailboxes(): Promise<any[]> { const session = await this.getSession(); const request: JmapRequest = { using: ['urn:ietf:params:jmap:core', 'urn:ietf:params:jmap:mail'], methodCalls: [ ['Mailbox/get', { accountId: session.accountId }, 'mailboxes'] ] }; const response = await this.makeRequest(request); return response.methodResponses[0][1].list; }
• src/index.ts:135-652 (registration)

  Registration of all MCP tools including 'list_mailboxes' via the ListToolsRequestSchema handler.
  server.setRequestHandler(ListToolsRequestSchema, async () => { return { tools: [ { name: 'list_mailboxes', description: 'List all mailboxes in the Fastmail account', inputSchema: { type: 'object', properties: {}, }, }, { name: 'list_emails', description: 'List emails from a mailbox', inputSchema: { type: 'object', properties: { mailboxId: { type: 'string', description: 'ID of the mailbox to list emails from (optional, defaults to all)', }, limit: { type: 'number', description: 'Maximum number of emails to return (default: 20)', default: 20, }, }, }, }, { name: 'get_email', description: 'Get a specific email by ID', inputSchema: { type: 'object', properties: { emailId: { type: 'string', description: 'ID of the email to retrieve', }, }, required: ['emailId'], }, }, { name: 'send_email', description: 'Send an email', inputSchema: { type: 'object', properties: { to: { type: 'array', items: { type: 'string' }, description: 'Recipient email addresses', }, cc: { type: 'array', items: { type: 'string' }, description: 'CC email addresses (optional)', }, bcc: { type: 'array', items: { type: 'string' }, description: 'BCC email addresses (optional)', }, from: { type: 'string', description: 'Sender email address (optional, defaults to account primary email)', }, mailboxId: { type: 'string', description: 'Mailbox ID to save the email to (optional, defaults to Drafts folder)', }, subject: { type: 'string', description: 'Email subject', }, textBody: { type: 'string', description: 'Plain text body (optional)', }, htmlBody: { type: 'string', description: 'HTML body (optional)', }, }, required: ['to', 'subject'], }, }, { name: 'search_emails', description: 'Search emails by subject or content', inputSchema: { type: 'object', properties: { query: { type: 'string', description: 'Search query string', }, limit: { type: 'number', description: 'Maximum number of results (default: 20)', default: 20, }, }, required: ['query'], }, }, { name: 'list_contacts', description: 'List contacts from the address book', inputSchema: { type: 'object', properties: { limit: { type: 'number', description: 'Maximum number of contacts to return (default: 50)', default: 50, }, }, }, }, { name: 'get_contact', description: 'Get a specific contact by ID', inputSchema: { type: 'object', properties: { contactId: { type: 'string', description: 'ID of the contact to retrieve', }, }, required: ['contactId'], }, }, { name: 'search_contacts', description: 'Search contacts by name or email', inputSchema: { type: 'object', properties: { query: { type: 'string', description: 'Search query string', }, limit: { type: 'number', description: 'Maximum number of results (default: 20)', default: 20, }, }, required: ['query'], }, }, { name: 'list_calendars', description: 'List all calendars', inputSchema: { type: 'object', properties: {}, }, }, { name: 'list_calendar_events', description: 'List events from a calendar', inputSchema: { type: 'object', properties: { calendarId: { type: 'string', description: 'ID of the calendar (optional, defaults to all calendars)', }, limit: { type: 'number', description: 'Maximum number of events to return (default: 50)', default: 50, }, }, }, }, { name: 'get_calendar_event', description: 'Get a specific calendar event by ID', inputSchema: { type: 'object', properties: { eventId: { type: 'string', description: 'ID of the event to retrieve', }, }, required: ['eventId'], }, }, { name: 'create_calendar_event', description: 'Create a new calendar event', inputSchema: { type: 'object', properties: { calendarId: { type: 'string', description: 'ID of the calendar to create the event in', }, title: { type: 'string', description: 'Event title', }, description: { type: 'string', description: 'Event description (optional)', }, start: { type: 'string', description: 'Start time in ISO 8601 format', }, end: { type: 'string', description: 'End time in ISO 8601 format', }, location: { type: 'string', description: 'Event location (optional)', }, participants: { type: 'array', items: { type: 'object', properties: { email: { type: 'string' }, name: { type: 'string' } } }, description: 'Event participants (optional)', }, }, required: ['calendarId', 'title', 'start', 'end'], }, }, { name: 'list_identities', description: 'List sending identities (email addresses that can be used for sending)', inputSchema: { type: 'object', properties: {}, }, }, { name: 'get_recent_emails', description: 'Get the most recent emails from inbox (like top-ten)', inputSchema: { type: 'object', properties: { limit: { type: 'number', description: 'Number of recent emails to retrieve (default: 10, max: 50)', default: 10, }, mailboxName: { type: 'string', description: 'Mailbox to search (default: inbox)', default: 'inbox', }, }, }, }, { name: 'mark_email_read', description: 'Mark an email as read or unread', inputSchema: { type: 'object', properties: { emailId: { type: 'string', description: 'ID of the email to mark', }, read: { type: 'boolean', description: 'true to mark as read, false to mark as unread', default: true, }, }, required: ['emailId'], }, }, { name: 'delete_email', description: 'Delete an email (move to trash)', inputSchema: { type: 'object', properties: { emailId: { type: 'string', description: 'ID of the email to delete', }, }, required: ['emailId'], }, }, { name: 'move_email', description: 'Move an email to a different mailbox', inputSchema: { type: 'object', properties: { emailId: { type: 'string', description: 'ID of the email to move', }, targetMailboxId: { type: 'string', description: 'ID of the target mailbox', }, }, required: ['emailId', 'targetMailboxId'], }, }, { name: 'get_email_attachments', description: 'Get list of attachments for an email', inputSchema: { type: 'object', properties: { emailId: { type: 'string', description: 'ID of the email', }, }, required: ['emailId'], }, }, { name: 'download_attachment', description: 'Download an email attachment', inputSchema: { type: 'object', properties: { emailId: { type: 'string', description: 'ID of the email', }, attachmentId: { type: 'string', description: 'ID of the attachment', }, }, required: ['emailId', 'attachmentId'], }, }, { name: 'advanced_search', description: 'Advanced email search with multiple criteria', inputSchema: { type: 'object', properties: { query: { type: 'string', description: 'Text to search for in subject/body', }, from: { type: 'string', description: 'Filter by sender email', }, to: { type: 'string', description: 'Filter by recipient email', }, subject: { type: 'string', description: 'Filter by subject', }, hasAttachment: { type: 'boolean', description: 'Filter emails with attachments', }, isUnread: { type: 'boolean', description: 'Filter unread emails', }, mailboxId: { type: 'string', description: 'Search within specific mailbox', }, after: { type: 'string', description: 'Emails after this date (ISO 8601)', }, before: { type: 'string', description: 'Emails before this date (ISO 8601)', }, limit: { type: 'number', description: 'Maximum results (default: 50)', default: 50, }, }, }, }, { name: 'get_thread', description: 'Get all emails in a conversation thread', inputSchema: { type: 'object', properties: { threadId: { type: 'string', description: 'ID of the thread/conversation', }, }, required: ['threadId'], }, }, { name: 'get_mailbox_stats', description: 'Get statistics for a mailbox (unread count, total emails, etc.)', inputSchema: { type: 'object', properties: { mailboxId: { type: 'string', description: 'ID of the mailbox (optional, defaults to all mailboxes)', }, }, }, }, { name: 'get_account_summary', description: 'Get overall account summary with statistics', inputSchema: { type: 'object', properties: {}, }, }, { name: 'bulk_mark_read', description: 'Mark multiple emails as read/unread', inputSchema: { type: 'object', properties: { emailIds: { type: 'array', items: { type: 'string' }, description: 'Array of email IDs to mark', }, read: { type: 'boolean', description: 'true to mark as read, false as unread', default: true, }, }, required: ['emailIds'], }, }, { name: 'bulk_move', description: 'Move multiple emails to a mailbox', inputSchema: { type: 'object', properties: { emailIds: { type: 'array', items: { type: 'string' }, description: 'Array of email IDs to move', }, targetMailboxId: { type: 'string', description: 'ID of target mailbox', }, }, required: ['emailIds', 'targetMailboxId'], }, }, { name: 'bulk_delete', description: 'Delete multiple emails (move to trash)', inputSchema: { type: 'object', properties: { emailIds: { type: 'array', items: { type: 'string' }, description: 'Array of email IDs to delete', }, }, required: ['emailIds'], }, }, { name: 'check_function_availability', description: 'Check which MCP functions are available based on account permissions', inputSchema: { type: 'object', properties: {}, }, }, { name: 'test_bulk_operations', description: 'Test bulk operations by finding recent emails and performing safe operations (mark read/unread)', inputSchema: { type: 'object', properties: { dryRun: { type: 'boolean', description: 'If true, only shows what would be done without making changes (default: true)', default: true, }, limit: { type: 'number', description: 'Number of emails to test with (default: 3, max: 10)', default: 3, }, }, }, }, ], }; });