#!/usr/bin/env node
// Slack MCP Server
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod";
import { readFile } from "fs/promises";
import { exec } from "child_process";
import { promisify } from "util";
const execAsync = promisify(exec);
const server = new McpServer({
name: "Slack Server",
version: "0.0.1",
});
// Slack image download tool
server.tool(
"slack_image_download",
"Download Slack images using authenticated curl command with SLACK_BOT_TOKEN",
{
url: z
.string()
.describe(
"Slack image URL to download (e.g., https://files.slack.com/files-tmb/T05EFSVDCLR-F08TC9CP9B8/screenshot_720.png or https://workspace.slack.com/files/U123/F456/image.png)",
),
},
async ({ url }) => {
try {
const slackToken = process.env.SLACK_BOT_TOKEN || process.env.SLACK_TOKEN;
if (!slackToken) {
throw new Error("SLACK_BOT_TOKEN or SLACK_TOKEN environment variable is required");
}
// Validate that it's a Slack URL (supports both files.slack.com and workspace.slack.com formats)
const slackUrlPattern = /^https:\/\/(?:files\.slack\.com\/files|[^.]+\.slack\.com\/files\/)/;
if (!slackUrlPattern.test(url)) {
throw new Error(
"URL must be a Slack file URL (e.g., https://files.slack.com/files/... or https://workspace.slack.com/files/...)",
);
}
// Extract file ID from URL
// Pattern: https://workspace.slack.com/files/USER_ID/FILE_ID/filename
// or https://files.slack.com/files-pri/TEAM_ID-FILE_ID/filename
const workspacePattern = /\/files\/[^\/]+\/([^\/]+)/;
const filesPattern = /\/files-pri\/[^-]+-([^\/]+)/;
let fileIdMatch = url.match(workspacePattern);
if (!fileIdMatch) {
fileIdMatch = url.match(filesPattern);
}
if (!fileIdMatch) {
throw new Error("Could not extract file ID from Slack URL");
}
const fileId = fileIdMatch[1];
// Use Slack Files API to get the download URL
const fileInfoResponse = await execAsync(
`curl -s -H "Authorization: Bearer ${slackToken}" "https://slack.com/api/files.info?file=${fileId}"`
);
const fileInfo = JSON.parse(fileInfoResponse.stdout);
if (!fileInfo.ok) {
if (fileInfo.error === 'missing_scope') {
throw new Error(`Slack bot token missing required scope: ${fileInfo.needed}. Current scopes: ${fileInfo.provided}`);
}
throw new Error(`Slack API error: ${fileInfo.error || 'Unknown error'}`);
}
const downloadUrl = fileInfo.file.url_private_download;
if (!downloadUrl) {
throw new Error("No download URL available for this file");
}
// Execute curl command with the proper download URL
const curlCommand = `curl -H "Authorization: Bearer ${slackToken}" "${downloadUrl}" -o slack_image.png`;
await execAsync(curlCommand);
// Check if the file was downloaded successfully
try {
const imageStats = await readFile("slack_image.png");
const fileSizeKB = Math.round(imageStats.length / 1024);
return {
content: [
{
type: "text",
text: `Successfully downloaded Slack image to slack_image.png (${fileSizeKB} KB)\nFrom URL: ${url}`,
},
],
};
} catch (readError) {
throw new Error(
"Image download may have failed - slack_image.png not found or empty",
);
}
} catch (error) {
const errorMessage =
error instanceof Error ? error.message : String(error);
return {
content: [
{
type: "text",
text: `Error downloading Slack image: ${errorMessage}`,
},
],
error: errorMessage,
isError: true,
};
}
},
);
async function runServer() {
const transport = new StdioServerTransport();
await server.connect(transport);
process.on("exit", () => {
server.close();
});
}
runServer().catch(console.error);
