import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";
import type { DiscordClient } from "../client.js";
import { formatMessage, formatMessageList } from "../formatters.js";
import { toolError, toolResult } from "./helpers.js";
export function registerMessageTools(
server: McpServer,
client: DiscordClient,
): void {
server.tool(
"discord_read_messages",
"Read recent messages from a Discord channel. Returns messages in chronological order (oldest first). Use 'before' for pagination to read further back in history.",
{
channel_id: z.string().describe("The channel ID to read from."),
limit: z
.number()
.min(1)
.max(100)
.optional()
.describe("Number of messages to fetch (1-100, default 25)."),
before: z
.string()
.optional()
.describe(
"Message ID — fetch messages before this one (for pagination backward).",
),
after: z
.string()
.optional()
.describe(
"Message ID — fetch messages after this one (for pagination forward).",
),
},
async ({ channel_id, limit, before, after }) => {
const messages = await client.getMessages(channel_id, {
limit: limit ?? 25,
before,
after,
});
return toolResult(formatMessageList(messages, { showPagination: true }));
},
);
server.tool(
"discord_send_message",
"Send a message to a Discord channel. Supports plain text and Discord markdown (bold, italic, code blocks). Returns the sent message ID.",
{
channel_id: z.string().describe("The channel ID to send to."),
content: z
.string()
.describe("Message content. Supports Discord markdown."),
reply_to: z
.string()
.optional()
.describe("Message ID to reply to (creates a threaded reply)."),
},
async ({ channel_id, content, reply_to }) => {
const msg = await client.sendMessage(channel_id, content, reply_to);
return toolResult(
`Message sent (ID: ${msg.id}).\n${formatMessage(msg)}`,
);
},
);
server.tool(
"discord_edit_message",
"Edit one of your own messages. You can only edit messages you sent.",
{
channel_id: z.string().describe("Channel containing the message."),
message_id: z.string().describe("ID of the message to edit."),
content: z.string().describe("New message content."),
},
async ({ channel_id, message_id, content }) => {
const msg = await client.editMessage(channel_id, message_id, content);
return toolResult(`Message edited (ID: ${msg.id}).\n${formatMessage(msg)}`);
},
);
server.tool(
"discord_delete_message",
"Delete one of your own messages. This action is permanent and cannot be undone.",
{
channel_id: z.string().describe("Channel containing the message."),
message_id: z.string().describe("ID of the message to delete."),
},
async ({ channel_id, message_id }) => {
try {
await client.deleteMessage(channel_id, message_id);
return toolResult(`Message ${message_id} deleted.`);
} catch (e) {
const msg = e instanceof Error ? e.message : String(e);
return toolError(`Failed to delete message: ${msg}`);
}
},
);
}
