WhatsApp MCP Server

Implementation Reference

• src/mcp.ts:341-385 (handler)

  The main handler function for the 'get_message_context' MCP tool. It calls getMessagesAround from the database module, formats the messages using formatDbMessageForJson, and returns the context as JSON or an error.
  async ({ message_id, before, after }) => { mcpLogger.info( `[MCP Tool] Executing get_message_context for msg ${message_id}, before=${before}, after=${after}`, ); try { const context = getMessagesAround(message_id, before, after); if (!context.target) { return { isError: true, content: [ { type: "text", text: `Message with ID ${message_id} not found.`, }, ], }; } const formattedContext = { target: formatDbMessageForJson(context.target), before: context.before.map(formatDbMessageForJson), after: context.after.map(formatDbMessageForJson), }; return { content: [ { type: "text", text: JSON.stringify(formattedContext, null, 2), }, ], }; } catch (error: any) { mcpLogger.error( `[MCP Tool Error] get_message_context failed for ${message_id}: ${error.message}`, ); return { isError: true, content: [ { type: "text", text: `Error retrieving context for message ${message_id}: ${error.message}`, }, ], }; } },
• src/mcp.ts:322-340 (schema)

  Zod input schema defining parameters for the get_message_context tool: message_id (required string), before and after (optional nonnegative integers defaulting to 5).
  { message_id: z .string() .describe("The ID of the target message to get context around"), before: z .number() .int() .nonnegative() .optional() .default(5) .describe("Number of messages before (default 5)"), after: z .number() .int() .nonnegative() .optional() .default(5) .describe("Number of messages after (default 5)"), },
• src/mcp.ts:320-386 (registration)

  Registration of the 'get_message_context' tool using server.tool() with schema and handler function.
  server.tool( "get_message_context", { message_id: z .string() .describe("The ID of the target message to get context around"), before: z .number() .int() .nonnegative() .optional() .default(5) .describe("Number of messages before (default 5)"), after: z .number() .int() .nonnegative() .optional() .default(5) .describe("Number of messages after (default 5)"), }, async ({ message_id, before, after }) => { mcpLogger.info( `[MCP Tool] Executing get_message_context for msg ${message_id}, before=${before}, after=${after}`, ); try { const context = getMessagesAround(message_id, before, after); if (!context.target) { return { isError: true, content: [ { type: "text", text: `Message with ID ${message_id} not found.`, }, ], }; } const formattedContext = { target: formatDbMessageForJson(context.target), before: context.before.map(formatDbMessageForJson), after: context.after.map(formatDbMessageForJson), }; return { content: [ { type: "text", text: JSON.stringify(formattedContext, null, 2), }, ], }; } catch (error: any) { mcpLogger.error( `[MCP Tool Error] get_message_context failed for ${message_id}: ${error.message}`, ); return { isError: true, content: [ { type: "text", text: `Error retrieving context for message ${message_id}: ${error.message}`, }, ], }; } }, );
• src/database.ts:292-351 (helper)

  Database helper function getMessagesAround that queries the SQLite database for messages before, the target message, and after the specified message ID, using timestamp ordering within the same chat.
  export function getMessagesAround( messageId: string, before: number = 5, after: number = 5, ): { before: Message[]; target: Message | null; after: Message[] } { const db = getDb(); const result: { before: Message[]; target: Message | null; after: Message[]; } = { before: [], target: null, after: [] }; try { const targetStmt = db.prepare(` SELECT m.*, c.name as chat_name FROM messages m JOIN chats c ON m.chat_jid = c.jid WHERE m.id = ? -- Positional parameter 1 `); const targetRow = targetStmt.get(messageId) as any | undefined; if (!targetRow) { return result; } result.target = rowToMessage(targetRow); const targetTimestamp = result.target.timestamp.toISOString(); const chatJid = result.target.chat_jid; const beforeStmt = db.prepare(` SELECT m.*, c.name as chat_name FROM messages m JOIN chats c ON m.chat_jid = c.jid WHERE m.chat_jid = ? AND m.timestamp < ? -- Positional params 1, 2 ORDER BY m.timestamp DESC LIMIT ? -- Positional param 3 `); const beforeRows = beforeStmt.all( chatJid, targetTimestamp, before, ) as any[]; result.before = beforeRows.map(rowToMessage).reverse(); const afterStmt = db.prepare(` SELECT m.*, c.name as chat_name FROM messages m JOIN chats c ON m.chat_jid = c.jid WHERE m.chat_jid = ? AND m.timestamp > ? -- Positional params 1, 2 ORDER BY m.timestamp ASC LIMIT ? -- Positional param 3 `); const afterRows = afterStmt.all(chatJid, targetTimestamp, after) as any[]; result.after = afterRows.map(rowToMessage); return result; } catch (error) { console.error("Error getting messages around:", error); return result; } }
• src/mcp.ts:20-35 (helper)

  Helper function to format database message objects into a JSON-friendly structure used in the tool handler.
  function formatDbMessageForJson(msg: DbMessage) { return { id: msg.id, chat_jid: msg.chat_jid, chat_name: msg.chat_name ?? "Unknown Chat", sender_jid: msg.sender ?? null, sender_display: msg.sender ? msg.sender.split("@")[0] : msg.is_from_me ? "Me" : "Unknown", content: msg.content, timestamp: msg.timestamp.toISOString(), is_from_me: msg.is_from_me, }; }