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Slack MCP Integration for LangGraph

Connect Slack to LangGraph through the local KosmoKrator MCP gateway with scoped tools, credentials, and write policy.

25 functions 13 read 12 write API token auth
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Connect Slack to LangGraph

Run KosmoKrator integration calls from LangGraph nodes while preserving local credentials and permissions.

Use a graph node that calls the KosmoKrator CLI for deterministic steps or an MCP client for dynamic tool selection. The gateway is local, scoped to this integration, and starts with --write=deny so LangGraph can inspect read-capable tools without receiving write access by default.

Slack MCP Config for LangGraph

Headless CLI calls fit repeatable graph edges; MCP fits exploratory agent nodes.

{
  "mcpServers": {
    "kosmokrator-slack": {
      "type": "stdio",
      "command": "kosmo",
      "args": [
        "mcp:serve",
        "--integration=slack",
        "--write=deny"
      ]
    }
  }
}

Run the Gateway Manually

kosmokrator mcp:serve --integration=slack --write=deny

Why Use KosmoKrator Here

Scoped tools

Expose only Slack instead of a broad multi-service tool list.

Local credentials

Reuse credentials already configured for the KosmoKrator CLI and Lua runtime.

Write policy

Start read-only, then opt into ask or allow for trusted workspaces.

Slack Tools Visible to LangGraph

LangGraph sees stable MCP tool names generated from the Slack integration catalog.

MCP toolSource functionTypeDescription
integration__slack__slack_send_message slack.slack_send_message Write Send a message to a Slack channel or DM. Supports text, blocks, and thread replies.
integration__slack__slack_update_message slack.slack_update_message Write Update an existing Slack message.
integration__slack__slack_delete_message slack.slack_delete_message Write Delete a message from a Slack channel.
integration__slack__slack_get_message slack.slack_get_message Read Get a specific message by its timestamp. Optionally fetch a message within a thread.
integration__slack__slack_search_messages slack.slack_search_messages Read Search for messages across all Slack channels and DMs.
integration__slack__slack_get_permalink slack.slack_get_permalink Read Get a permalink URL for a specific Slack message.
integration__slack__slack_get_channel_history slack.slack_get_channel_history Read Get message history for a Slack channel. Supports pagination with cursors.
integration__slack__slack_get_thread_replies slack.slack_get_thread_replies Read Get all replies in a Slack message thread.
integration__slack__slack_list_channels slack.slack_list_channels Read List all Slack channels the bot has access to.
integration__slack__slack_get_channel slack.slack_get_channel Read Get detailed information about a Slack channel.
integration__slack__slack_create_channel slack.slack_create_channel Write Create a new Slack channel.
integration__slack__slack_set_topic slack.slack_set_topic Write Set the topic for a Slack channel.
integration__slack__slack_set_purpose slack.slack_set_purpose Write Set the purpose for a Slack channel.
integration__slack__slack_archive_channel slack.slack_archive_channel Write Archive a Slack channel.
integration__slack__slack_invite_to_channel slack.slack_invite_to_channel Write Invite one or more users to a Slack channel.
integration__slack__slack_upload_file slack.slack_upload_file Write Upload a file to Slack using the modern external upload flow. The file content is posted to a channel or as a thread reply.
integration__slack__slack_list_files slack.slack_list_files Read List files in Slack, optionally filtered by channel, user, or file type.
integration__slack__slack_get_file slack.slack_get_file Read Get detailed information about a Slack file.
integration__slack__slack_list_users slack.slack_list_users Read List all users in the Slack workspace.
integration__slack__slack_get_user slack.slack_get_user Read Get detailed information about a Slack user by their user ID.
integration__slack__slack_find_user_by_email slack.slack_find_user_by_email Read Look up a Slack user by their email address.
integration__slack__slack_add_reaction slack.slack_add_reaction Write Add an emoji reaction to a Slack message.
integration__slack__slack_remove_reaction slack.slack_remove_reaction Write Remove an emoji reaction from a Slack message.
integration__slack__slack_list_usergroups slack.slack_list_usergroups Read List all usergroups in the Slack workspace.
integration__slack__slack_update_usergroup_members slack.slack_update_usergroup_members Write Update the members of a Slack usergroup.

Related Slack Pages

Slack CLIUse direct JSON commands instead of MCP discovery. Slack MCPFull gateway reference and MCP tool names. KosmoKrator for LangGraphClient-level gateway setup.