WhatsApp MCP Server

Implementation Reference

• src/mcp.ts:280-317 (handler)

  MCP tool handler for 'get_chat': logs execution, calls getChat from database, formats the chat with formatDbChatForJson, returns JSON or error.

  async ({ chat_jid, include_last_message }) => {
    mcpLogger.info(
      `[MCP Tool] Executing get_chat for ${chat_jid}, lastMsg=${include_last_message}`,
    );
    try {
      const chat = getChat(chat_jid, include_last_message);
      if (!chat) {
        return {
          isError: true,
          content: [
            { type: "text", text: `Chat with JID ${chat_jid} not found.` },
          ],
        };
      }
      const formattedChat = formatDbChatForJson(chat);
      return {
        content: [
          {
            type: "text",
            text: JSON.stringify(formattedChat, null, 2),
          },
        ],
      };
    } catch (error: any) {
      mcpLogger.error(
        `[MCP Tool Error] get_chat failed for ${chat_jid}: ${error.message}`,
      );
      return {
        isError: true,
        content: [
          {
            type: "text",
            text: `Error retrieving chat ${chat_jid}: ${error.message}`,
          },
        ],
      };
    }
  },

• src/mcp.ts:272-279 (schema)

  Zod input schema for 'get_chat' tool defining parameters chat_jid (required string) and optional include_last_message (boolean, default true).

  {
    chat_jid: z.string().describe("The JID of the chat to retrieve"),
    include_last_message: z
      .boolean()
      .optional()
      .default(true)
      .describe("Include last message details (default true)"),
  },

• src/mcp.ts:270-318 (registration)

  Registration of the 'get_chat' MCP tool using server.tool, including inline schema and handler function.

  server.tool(
    "get_chat",
    {
      chat_jid: z.string().describe("The JID of the chat to retrieve"),
      include_last_message: z
        .boolean()
        .optional()
        .default(true)
        .describe("Include last message details (default true)"),
    },
    async ({ chat_jid, include_last_message }) => {
      mcpLogger.info(
        `[MCP Tool] Executing get_chat for ${chat_jid}, lastMsg=${include_last_message}`,
      );
      try {
        const chat = getChat(chat_jid, include_last_message);
        if (!chat) {
          return {
            isError: true,
            content: [
              { type: "text", text: `Chat with JID ${chat_jid} not found.` },
            ],
          };
        }
        const formattedChat = formatDbChatForJson(chat);
        return {
          content: [
            {
              type: "text",
              text: JSON.stringify(formattedChat, null, 2),
            },
          ],
        };
      } catch (error: any) {
        mcpLogger.error(
          `[MCP Tool Error] get_chat failed for ${chat_jid}: ${error.message}`,
        );
        return {
          isError: true,
          content: [
            {
              type: "text",
              text: `Error retrieving chat ${chat_jid}: ${error.message}`,
            },
          ],
        };
      }
    },
  );

• src/mcp.ts:37-52 (helper)

  Helper function to format database Chat object to JSON-friendly structure for the get_chat tool response.

  function formatDbChatForJson(chat: DbChat) {
    return {
      jid: chat.jid,
      name: chat.name ?? chat.jid.split("@")[0] ?? "Unknown Chat",
      is_group: chat.jid.endsWith("@g.us"),
      last_message_time: chat.last_message_time?.toISOString() ?? null,
      last_message_preview: chat.last_message ?? null,
      last_sender_jid: chat.last_sender ?? null,
      last_sender_display: chat.last_sender
        ? chat.last_sender.split("@")[0]
        : chat.last_is_from_me
          ? "Me"
          : null,
      last_is_from_me: chat.last_is_from_me ?? null,
    };
  }

• src/database.ts:259-290 (helper)

  Database function getChat that queries SQLite for a specific chat by JID, optionally includes last message details, used by the MCP get_chat handler.

  export function getChat(
    jid: string,
    includeLastMessage: boolean = true,
  ): Chat | null {
    const db = getDb();
    try {
      let sql = `
              SELECT
                  c.jid,
                  c.name,
                  c.last_message_time
                  ${
                    includeLastMessage
                      ? `,
                  (SELECT m.content FROM messages m WHERE m.chat_jid = c.jid ORDER BY m.timestamp DESC LIMIT 1) as last_message,
                  (SELECT m.sender FROM messages m WHERE m.chat_jid = c.jid ORDER BY m.timestamp DESC LIMIT 1) as last_sender,
                  (SELECT m.is_from_me FROM messages m WHERE m.chat_jid = c.jid ORDER BY m.timestamp DESC LIMIT 1) as last_is_from_me
                  `
                      : ""
                  }
              FROM chats c
              WHERE c.jid = ? -- Positional parameter 1
          `;
  
      const stmt = db.prepare(sql);
      const row = stmt.get(jid) as any | undefined;
      return row ? rowToChat(row) : null;
    } catch (error) {
      console.error("Error getting chat:", error);
      return null;
    }
  }