How to Connect Slack

🔧 Tools · MCP

Slack's hosted MCP server at https://mcp.slack.com/mcp lets the agent search messages and files, read channel and DM history, post messages, and read or write canvases — scoped to the user that authorized the connection.

1. Create a Slack App

1. At api.slack.com/apps, Create New App → From scratch. Name it Zeta Alpha MCP and pick the target workspace.

2. Under Agents & AI Apps, enable Model Context Protocol.

3. (Enterprise Grid only) Under Org Level Apps, enable Enable org-readiness so an org admin can install the app once and grant it to multiple workspaces — see Slack's docs on organization-ready apps.

4. Under OAuth & Permissions:

   • Redirect URLs — click Add New Redirect URL, enter https://api.zeta-alpha.com/v0/service/mcp/oauth/callback/ (trailing slash required), then Add and Save URLs.

   • Advanced token security via token rotation — opt in. The MCP client refreshes tokens automatically.

   • User Token Scopes — add only what the agent needs (Slack admins approve focused apps more readily):

     search:read.public search:read.private search:read.mpim search:read.im
     search:read.files search:read.users files:read chat:write
     channels:history groups:history mpim:history im:history
     canvases:read canvases:write users:read users:read.email

5. Copy the Client ID and Client Secret from Basic Information → App Credentials.

2. Add the Server to the Agent

In Platform Admin, open the agent's Configuration and add this entry to mcp_tools_provider_configuration.servers (see Connecting MCP Servers):

{
  "transport": "streamable-http",
  "transport_config": {
    "streamable_http": {
      "url": "https://mcp.slack.com/mcp",
      "name": "slack",
      "timeout": 30,
      "oauth_client": {
        "server_url": "https://mcp.slack.com/mcp",
        "client_id": "<Slack Client ID>",
        "client_secret": "<Slack Client secret>",
        "client_metadata": {
          "client_name": "Zeta Alpha MCP",
          "scope": "search:read.public search:read.private search:read.mpim search:read.im search:read.files search:read.users files:read chat:write channels:history groups:history mpim:history im:history canvases:read canvases:write users:read users:read.email",
          "grant_types": ["authorization_code", "refresh_token"],
          "response_types": ["code"],
          "token_endpoint_auth_method": "client_secret_post",
          "redirect_uris": [
            "https://api.zeta-alpha.com/v0/service/mcp/oauth/callback/"
          ]
        }
      },
      "terminate_on_close": true
    }
  }
}

client_metadata.scope must be a subset of the User Token Scopes on the app.

3. Connect from the Navigator

In a new chat, ask the agent for something that needs Slack (e.g. "Find recent messages mentioning the Q3 roadmap") and follow the Authorize prompt — see Connecting from the Navigator.

If the workspace requires admin approval for new apps, the user sees a "Request approval" screen — an admin needs to approve it once.

Troubleshooting

Symptom	Cause
bad_redirect_uri	Trailing-slash mismatch between the Slack app and redirect_uris.
invalid_scope during authorization	A scope in client_metadata.scope isn't enabled under User Token Scopes.
missing_scope at tool-call time	User authorized before a new scope was added. Re-authorize.
not_in_channel when posting	User isn't a member of the target channel.