Slack MCP Server
Server Configuration
Describes the environment variables required to run the server.
| Name | Required | Description | Default |
|---|---|---|---|
| SLACK_MCP_ADD_MESSAGE_TOOL | No | Controls message posting capability. Set to '*' to enable for all channels, or provide comma-separated channel IDs (e.g., 'C1234567890,C9876543210') to enable for specific channels. If not set, message posting is disabled by default. |
Instructions
Guidance the server publishes about itself, which clients place ahead of the tool catalog so the model reads it before choosing anything.
This server publishes no instructions, or was last inspected before Glama recorded them.
Capabilities
Server capabilities have not been inspected yet.
Tools
Functions exposed to the LLM to take actions
| Name | Description |
|---|---|
| conversations_historyB | Retrieves message history from a Slack channel, DM, or thread. Supports pagination and filtering. |
| conversations_repliesA | Fetches all messages in a specific thread by channel and thread timestamp. Supports pagination. |
| conversations_add_messageA | Posts a message to a channel, thread, or DM. Supports markdown and plain text. NOTE: Disabled by default for safety - set SLACK_MCP_ADD_MESSAGE_TOOL environment variable to enable. |
| channels_listA | Lists workspace channels by type (public, private, DMs, group DMs) with optional popularity sorting. Supports pagination. |
Prompts
Interactive templates invoked by user choice
| Name | Description |
|---|---|
No prompts | |
Resources
Contextual data attached and managed by the client
| Name | Description |
|---|---|
No resources | |
TDQS
Scored across 4 tools
Each tool has a clearly distinct purpose: channels_list lists channels, conversations_add_message posts messages, conversations_history retrieves channel history, and conversations_replies fetches thread replies. There is no overlap in functionality, making it easy for an agent to select the correct tool.
The tool names follow a consistent snake_case pattern and use descriptive verbs like 'list', 'add', and 'history'. However, 'channels_list' deviates slightly from the 'conversations_' prefix used by the other three tools, which is a minor inconsistency.
With only 4 tools, the server feels thin for a Slack integration, as it lacks common operations like updating or deleting messages, managing users, or handling reactions. While the tools cover basic messaging and channel listing, the scope is limited, potentially requiring workarounds for full Slack workflows.
The tool set is significantly incomplete for a Slack server. It covers listing channels and basic message operations (posting, retrieving history, and thread replies), but misses essential CRUD actions like editing or deleting messages, user management, file handling, and event subscriptions. This will likely cause agent failures in more complex interactions.