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Slack MCP Server

Slack MCP Server

by Arnabdaz
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Remote

Slack MCP Server

Search and read public-channel Slack discussions about Jira tickets and PRs, and send/reply to messages only after an explicit two-step confirmation.

What it can and can't do

  • Reads public channels only. DMs, private channels, and group DMs are refused by a server-side guard — even though the user token could see them.

  • Search uses Slack's search.messages, which requires a user token.

  • Sending is two-step: draft_message returns a preview + one-time token; nothing posts until you call send_message with that token.

Related MCP server: Slack MCP Server

Slack app setup

  1. Create an app at https://api.slack.com/apps.

  2. Under OAuth & Permissions → User Token Scopes, add: search:read, channels:history, channels:read, users:read, chat:write.

  3. Install the app to your workspace and copy the User OAuth Token (xoxp-...).

Configuration

export SLACK_USER_TOKEN="xoxp-..."          # required
export SLACK_DRAFT_TTL_SECONDS=300           # optional, default 300

Run

uv sync
uv run slack-mcp

MCP client config

{
  "mcpServers": {
    "slack": {
      "command": "uv",
      "args": ["run", "slack-mcp"],
      "cwd": "/absolute/path/to/slack-mcp",
      "env": { "SLACK_USER_TOKEN": "xoxp-..." }
    }
  }
}

Tools

  • search_messages(query, count=20) — find messages in public channels.

  • read_thread(channel, thread_ts) — full thread with resolved names.

  • read_channel_history(channel, limit=30, around_ts=None) — recent/context.

  • list_channels(name_filter=None) — public channels.

  • resolve_users(user_ids) — ids → display names.

  • draft_message(channel, text, thread_ts=None) — preview + token; does NOT send.

  • send_message(confirmation_token) — sends the drafted message (only write path).

Available Tools

7 tools
draft_messageA

Prepare a message for sending and return a preview + confirmation token.

THIS DOES NOT SEND ANYTHING. It validates the target is a public channel, renders exactly what would be posted, and returns a one-time confirmation_token. To actually post, the user must review this preview and then call send_message(confirmation_token=...). Always show the user this preview and get their explicit approval before calling send_message.

Args: channel: Channel id or "#name". Must be a public channel. text: The exact message text to post. thread_ts: Optional thread root timestamp to reply in a thread.

Inputs: text (required), channel (required), thread_ts. Returns: object

list_channelsA
Read-only

List PUBLIC channels, optionally filtered by a name substring.

Args: name_filter: Optional case-insensitive substring to match channel names.

Inputs: name_filter. Returns: object

read_channel_historyA
Read-only

Read recent messages from a PUBLIC channel, or messages around a timestamp.

Args: channel: Channel id or "#name". Must be a public channel. limit: Number of messages (1-100, default 30). around_ts: Optional message timestamp; returns messages up to and including it, for context around a specific point.

Inputs: channel (required), limit, around_ts. Returns: object

read_threadA
Read-only

Read a full thread (root message + all replies) from a PUBLIC channel.

Args: channel: Channel id (e.g. "C0123") or "#name". Must be a public channel. thread_ts: The thread's root timestamp (the ts of the first message).

Inputs: channel (required), thread_ts (required). Returns: object

resolve_usersA
Read-only

Resolve Slack user ids (e.g. "U0123") to display names.

Args: user_ids: List of Slack user ids to resolve.

Inputs: user_ids (required). Returns: object

search_messagesA
Read-only

Search Slack messages in PUBLIC channels only.

Use this to find discussions about a Jira ticket or PR by passing the ticket key (e.g. "DSE-1234"), a PR URL, or free-text keywords as the query. Results from DMs and private channels are never returned.

Args: query: Search text — a ticket key, PR URL, or keywords. count: Max results (1-100, default 20).

Inputs: query (required), count. Returns: object

send_messageA

Send a previously drafted message. Requires a valid confirmation_token from draft_message. This is the ONLY tool that posts to Slack.

Only call this after the user has reviewed the draft_message preview and explicitly approved sending.

Args: confirmation_token: The one-time token returned by draft_message.

Inputs: confirmation_token (required). Returns: object

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

Loading tool schema changelog…

    Deploy Server
    One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

    TDQS

    A4.2/5.0

    Scored across 7 tools

    Disambiguation5/5

    Each tool has a clearly distinct purpose: searching, reading threads, reading channel history, listing channels, resolving users, drafting, and sending. The only potential overlap between read_thread and read_channel_history is clarified by their specific scopes (thread vs channel).

    Naming Consistency5/5

    All tool names follow the verb_noun pattern with snake_case (search_messages, read_thread, read_channel_history, list_channels, resolve_users, draft_message, send_message). No mixed conventions or vague verbs.

    Tool Count5/5

    7 tools is well-scoped for a Slack server covering search, read, list, resolve, and send operations. Each tool earns its place without redundancy or bloat.

    Completeness5/5

    The toolset covers the core lifecycle for public channel messaging: searching, reading history, reading threads, listing channels, resolving users, and sending with a safe draft/approve flow. No obvious dead ends for common use cases.

    Maintenance

    ActivityInactive
    ResponsivenessOutdated data

    Resources

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