Mcp Slack — independently scanned and version-tracked by SaferSkills.
SaferSkills independently audited Mcp Slack (Agent Skill) and scored it 100/100 (green). The audit ran 55 deterministic rules across Security, Supply Chain, Maintenance, Transparency, and Community; it found 0 high-severity and 0 lower-severity findings. The full rule-by-rule trace and per-finding evidence are below. Free, methodology-open.
Findings & checks · 0 flagged
Every scanned point with the score it earned and what moved between them.
First recorded scan — no prior version to compare against.
The primary manifest — the file an agent reads to learn what this artifact does.
Secure MCP server for Slack workspaces. Provides Claude Code (and other MCP clients) with read access to your Slack channels, messages, users, and files, and can send a message on your behalf.
readOnlyHint: true. The other two send a message and cancel a scheduled one; nothing edits or deletes existing content.xoxp- tokens for user-scoped access to your workspace.httpx directly for minimal, auditable HTTP calls.claude mcp add mcp-slack-crunchtools \
--env SLACK_USER_TOKEN=xoxp-your-token \
-- uvx mcp-slack-crunchtoolsclaude mcp add mcp-slack-crunchtools \
--env SLACK_USER_TOKEN=xoxp-your-token \
-- podman run -i --rm -e SLACK_USER_TOKEN quay.io/crunchtools/mcp-slackclaude mcp add mcp-slack-crunchtools \
--env SLACK_USER_TOKEN=xoxp-your-token \
-- uv run mcp-slack-crunchtoolsSee CLAUDE.md for detailed instructions on creating a Slack app and obtaining a User OAuth Token.
Authentication uses one of two mutually exclusive modes. The server picks cookie mode when both cookie variables are set, and token mode otherwise.
| Variable | Required | Default | Description |
|---|---|---|---|
SLACK_USER_TOKEN | token mode | — | User OAuth token (xoxp-...) from a Slack app installed in the workspace. |
SLACK_COOKIE_TOKEN | cookie mode | — | Browser session token (xoxc-...). Must be paired with SLACK_COOKIE_D. |
SLACK_COOKIE_D | cookie mode | — | Value of the d cookie (xoxd-...) from the same browser session. Sent as a Cookie: header alongside SLACK_COOKIE_TOKEN. |
SLACK_ADD_MESSAGE_DELAY | no | 3m | How far ahead outgoing messages are scheduled, giving you a window to cancel one. Duration string: 30s, 5m, 2h, or a bare integer for seconds. Set to 0, 0s, none, or false to disable scheduling and post immediately. |
Cookie mode is the working path for this deployment. Token mode requires a Slack app to be created and approved in the workspace; where that approval is not available, cookie mode is the only way to authenticate at all.
Cookie mode borrows an existing browser session rather than holding a credential issued to an application. That has consequences worth stating plainly:
in Slack, with your full access. Treat them exactly as you would your password.
re-extraction. A sudden wave of auth failures usually means the session rotated, not that the server broke.
time. Cookie mode is a workaround for the absence of an approved app, not a supported integration path.
Prefer SLACK_USER_TOKEN whenever a Slack app can actually be installed.
| Tool | Description |
|---|---|
slack_auth_test | Test connection and get token owner info |
slack_list_channels | List workspace channels |
slack_get_channel_info | Get channel details |
slack_get_channel_history | Read channel messages |
slack_get_thread_replies | Read thread replies |
slack_list_channel_members | List channel members |
slack_search_messages | Search messages |
slack_get_reactions | Get message reactions |
slack_list_reactions | List user's reactions |
slack_list_stars | List starred items |
slack_get_user_info | Get user details |
slack_list_users | List workspace members |
slack_get_user_profile | Get user profile |
slack_list_files | List files (metadata only) |
slack_get_file_info | Get file metadata |
slack_send_message | Schedule a message SLACK_ADD_MESSAGE_DELAY ahead, or post it immediately when the delay is 0 (write) |
slack_cancel_scheduled_message | Cancel a scheduled message before it sends (write) |
The two write tools need the chat:write scope in token mode.
See SECURITY.md for the full security design document.
AGPL-3.0-or-later
<!-- mcp-name: io.github.crunchtools/slack -->
~30 seconds. Free. No account. Every finding cites a rule and a line of evidence.