JMAP MCP Server

Implementation Reference

• index.js:237-307 (handler)

  The handler function that implements the core logic for retrieving full email content by ID. It fetches email metadata and body (text/HTML) using JMAP API, downloads blobs if needed, and formats the output as structured text.

  async ({ emailId }) => {
    const session = await jam.session;
    const accountId = session.primaryAccounts["urn:ietf:params:jmap:mail"];
    const [emails] = await jam.api.Email.get({
      accountId,
      ids: [emailId],
      properties: ["id", "textBody", "htmlBody", "subject", "from", "to", "cc", "bcc", "sentAt", "receivedAt"]
    });
  
    if (!emails || emails.list.length === 0) {
      return {
        content: [{
          type: "text",
          text: `Error: Email with ID ${emailId} not found.`
        }],
        isError: true
      };
    }
  
    const email = emails.list[0];
  
    let bodyContent = 'No body content found.';
  
    const downloadBodyPartContent = async (bodyPart) => {
      if (!bodyPart || !bodyPart.blobId) {
        return null;
      }
      try {
        const response = await jam.downloadBlob({
          accountId,
          blobId: bodyPart.blobId,
          mimeType: bodyPart.type || 'application/octet-stream', // Use part type or a default
          fileName: bodyPart.name || 'body_part' // Use part name or a default
        });
        if (response.ok) {
          return response.text(); // Read the response body as text
        } else {
          console.error(`Failed to download blob ${bodyPart.blobId}: ${response.status} ${response.statusText}`);
          return null;
        }
      } catch (error) {
        console.error(`Error downloading blob ${bodyPart.blobId}:`, error);
        return null;
      }
    };
  
    // Prioritize text body, then HTML body
    if (email.textBody && email.textBody.length > 0) {
      // Assuming we only need the content of the first text part for simplicity
      const firstTextPart = email.textBody[0];
      const downloadedText = await downloadBodyPartContent(firstTextPart);
      if (downloadedText !== null) {
        bodyContent = downloadedText;
      }
    } else if (email.htmlBody && email.htmlBody.length > 0) {
       // Assuming we only need the content of the first html part for simplicity
      const firstHtmlPart = email.htmlBody[0];
      const downloadedHtml = await downloadBodyPartContent(firstHtmlPart);
       // Note: For HTML body, you might want to strip HTML tags for a text representation
      if (downloadedHtml !== null) {
        bodyContent = `[HTML Body - may contain tags]\n${downloadedHtml}`; // Indicate it's HTML
      }
    }
  
    return {
      content: [{
        type: "text",
        text: `Subject: ${email.subject || '(No Subject)'}\nFrom: ${email.from ? email.from.map(f => f.name ? `${f.name} <${f.email}>` : f.email).join(', ') : '(Unknown Sender)'}\nTo: ${email.to ? email.to.map(t => t.name ? `${t.name} <${t.email}>` : t.email).join(', ') : '(Unknown Recipient)'}\nDate: ${email.receivedAt || email.sentAt || '(Unknown Date)'}\n\n---\n\n${bodyContent}`
      }]
    };
  }

• index.js:231-236 (schema)

  Input schema and description for the get_email_content tool, using Zod for validation of the emailId parameter.

  {
    description: "Retrieves the full content of an email by its ID, including subject, sender, recipients, date, and body (text or HTML).",
    inputSchema: z.object({
      emailId: z.string().describe("The ID of the email to fetch.")
    })
  },

• index.js:229-230 (registration)

  Registration of the get_email_content tool on the MCP server via server.tool() call.

  server.tool(
    "get_email_content",

• index.js:260-281 (helper)

  Nested helper function used by the handler to download email body part content from JMAP blobs.

  const downloadBodyPartContent = async (bodyPart) => {
    if (!bodyPart || !bodyPart.blobId) {
      return null;
    }
    try {
      const response = await jam.downloadBlob({
        accountId,
        blobId: bodyPart.blobId,
        mimeType: bodyPart.type || 'application/octet-stream', // Use part type or a default
        fileName: bodyPart.name || 'body_part' // Use part name or a default
      });
      if (response.ok) {
        return response.text(); // Read the response body as text
      } else {
        console.error(`Failed to download blob ${bodyPart.blobId}: ${response.status} ${response.statusText}`);
        return null;
      }
    } catch (error) {
      console.error(`Error downloading blob ${bodyPart.blobId}:`, error);
      return null;
    }
  };