Slack Message MCP
Tiny MCP server that exposes one tool over stdio or HTTP:
post_slack_messageposts text to the Slack channel ID provided by the caller
Environment
Set these before starting the server:
export SLACK_BOT_TOKEN="xoxb-..."The Slack app needs chat:write and must be allowed to post in the target channel.
Optional for the HTTP server:
export PORT="3000"The HTTP server does not perform app-level authentication. Deploy it only where the managed agent runtime or private network controls who can reach the endpoint.
Run Locally With Stdio
node server.jsClaude Code Example
claude mcp add slack-message \
--env SLACK_BOT_TOKEN="$SLACK_BOT_TOKEN" \
-- node /Users/agruning/Documents/MCP/slack-message-mcp/server.jsRun As Remote HTTP MCP
Claude managed agents and the Claude API MCP connector cannot connect to local stdio servers. Deploy the HTTP server behind a public HTTPS URL:
npm run start:httpThe MCP endpoint is:
POST /mcpHealth check:
GET /healthClaude managed agent / Messages API shape:
{
"mcp_servers": [
{
"type": "url",
"url": "https://your-domain.example.com/mcp",
"name": "Slack"
}
],
"tools": [
{
"type": "mcp_toolset",
"mcp_server_name": "Slack",
"default_config": {
"enabled": false
},
"configs": {
"post_slack_message": {
"enabled": true
}
}
}
]
}Use the beta header required by Anthropic's MCP connector:
anthropic-beta: mcp-client-2025-11-20Tool call arguments:
{
"channel": "C0123456789",
"text": "Hello from MCP"
}
