reply_email

Instructions

Implementation Reference

• src/index.ts:243-292 (registration)

  Tool registration for 'reply_email' in ListToolsRequestSchema handler: defines name, description, and inputSchema (with properties: originalEmailId, to, cc, bcc, from, textBody, htmlBody, send, replyTo)

  {
    name: 'reply_email',
    description: 'Reply to an existing email with proper threading headers (In-Reply-To, References). Automatically fetches the original email to build the reply chain. By default sends immediately; set send=false to save as a draft instead.',
    inputSchema: {
      type: 'object',
      properties: {
        originalEmailId: {
          type: 'string',
          description: 'ID of the email to reply to',
        },
        to: {
          type: 'array',
          items: { type: 'string' },
          description: 'Recipient email addresses (optional, defaults to the original sender)',
        },
        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)',
        },
        textBody: {
          type: 'string',
          description: 'Plain text body (optional)',
        },
        htmlBody: {
          type: 'string',
          description: 'HTML body (optional)',
        },
        send: {
          type: ['boolean', 'string'],
          description: 'Whether to send the reply immediately (default: true). Set to false to save as draft instead.',
        },
        replyTo: {
          type: 'array',
          items: { type: 'string' },
          description: 'Reply-To email addresses (replies go here instead of to the sender)',
        },
      },
      required: ['originalEmailId'],
    },
  },

• src/index.ts:1079-1155 (handler)

  Handler for 'reply_email' in CallToolRequestSchema switch statement: fetches original email, builds threading headers (In-Reply-To, References), prepends 'Re:' to subject, defaults recipients to original sender, then either creates a draft (if send=false) or sends the reply email via JmapClient.

  case 'reply_email': {
    const { originalEmailId, to, cc, bcc, from, textBody, htmlBody, send, replyTo } = args as any;
    const shouldSend = coerceBool(send) ?? true;
    if (!originalEmailId) {
      throw new McpError(ErrorCode.InvalidParams, 'originalEmailId is required');
    }
    if (shouldSend && !textBody && !htmlBody) {
      throw new McpError(ErrorCode.InvalidParams, 'Either textBody or htmlBody is required');
    }
  
    // Fetch the original email to get threading headers
    const originalEmail = await client.getEmailById(originalEmailId);
  
    // Build threading headers
    const originalMessageId = originalEmail.messageId?.[0];
    if (!originalMessageId) {
      throw new McpError(ErrorCode.InternalError, 'Original email does not have a Message-ID; cannot thread reply');
    }
  
    const inReplyToHeader = [originalMessageId];
    const referencesHeader = [
      ...(originalEmail.references || []),
      originalMessageId,
    ];
  
    // Build subject with Re: prefix
    let replySubject = originalEmail.subject || '';
    if (!/^Re:/i.test(replySubject)) {
      replySubject = `Re: ${replySubject}`;
    }
  
    // Default recipients to the original sender
    const toArray = coerceStringArray(to);
    const replyRecipients = (toArray && toArray.length > 0)
      ? toArray
      : (Array.isArray(originalEmail.from) ? originalEmail.from.map((addr: any) => addr.email).filter(Boolean) : []);
  
    if (replyRecipients.length === 0) {
      throw new McpError(ErrorCode.InvalidParams, 'Could not determine reply recipient. Please provide "to" explicitly.');
    }
  
    const replyParams = {
      to: replyRecipients,
      cc,
      bcc,
      from,
      subject: replySubject,
      textBody,
      htmlBody,
      inReplyTo: inReplyToHeader,
      references: referencesHeader,
      replyTo,
    };
  
    if (!shouldSend) {
      const emailId = await client.createDraft(replyParams);
      return {
        content: [
          {
            type: 'text',
            text: `Reply draft saved successfully (Email ID: ${emailId}). Subject: ${replySubject}`,
          },
        ],
      };
    }
  
    const submissionId = await client.sendEmail(replyParams);
  
    return {
      content: [
        {
          type: 'text',
          text: `Reply sent successfully. Submission ID: ${submissionId}`,
        },
      ],
    };
  }

• src/index.ts:248-291 (schema)

  Input schema for reply_email: defines originalEmailId (required), to, cc, bcc, from, textBody, htmlBody, send (default true), and replyTo fields.

    properties: {
      originalEmailId: {
        type: 'string',
        description: 'ID of the email to reply to',
      },
      to: {
        type: 'array',
        items: { type: 'string' },
        description: 'Recipient email addresses (optional, defaults to the original sender)',
      },
      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)',
      },
      textBody: {
        type: 'string',
        description: 'Plain text body (optional)',
      },
      htmlBody: {
        type: 'string',
        description: 'HTML body (optional)',
      },
      send: {
        type: ['boolean', 'string'],
        description: 'Whether to send the reply immediately (default: true). Set to false to save as draft instead.',
      },
      replyTo: {
        type: 'array',
        items: { type: 'string' },
        description: 'Reply-To email addresses (replies go here instead of to the sender)',
      },
    },
    required: ['originalEmailId'],
  },