Slack

​

Example seed

{
  "name": "Slack eval fixture",
  "twins": [
    "slack"
  ],
  "seed_config": {
    "slack": {
      "channels": [
        {
          "name": "channel-name",
          "is_private": false,
          "messages": [
            {
              "text": "message text",
              "user": "username",
              "pinned": false,
              "metadata": {
                "entities": []
              },
              "reactions": [
                {
                  "name": "thumbsup",
                  "users": [
                    "another.username"
                  ]
                }
              ],
              "replies": [
                {
                  "text": "thread reply",
                  "user": "another.username",
                  "reply_broadcast": false
                }
              ]
            }
          ]
        }
      ],
      "direct_messages": [
        {
          "users": [
            "slack-twin-bot",
            "username"
          ],
          "messages": [
            {
              "text": "direct message text",
              "user": "username"
            }
          ]
        }
      ],
      "users": [
        {
          "name": "username",
          "real_name": "User Name",
          "email": "user@example.com"
        }
      ],
      "canvases": [
        {
          "title": "Runbook",
          "channel": "channel-name",
          "markdown": "# Runbook\nSeeded canvas content."
        }
      ],
      "oauth_bot_scopes": [
        "chat:write",
        "channels:read",
        "channels:history",
        "users:read"
      ],
      "oauth_user_scopes": [
        "search:read",
        "channels:read",
        "channels:history"
      ],
      "tokens": [
        {
          "token": "xoxb-custom-token",
          "user_id": "UTWINBOT",
          "scopes": [
            "chat:write",
            "channels:read",
            "files:write",
            "files:read"
          ],
          "is_bot": true
        }
      ],
      "file_uploads_enabled": true,
      "max_storage_bytes": 5368709120,
      "storage_used_bytes": 0,
      "event_delivery": {
        "auto_dispatch": true,
        "use_wall_clock_signatures": true
      },
      "rate_limiting_enabled": false,
      "rate_limits": {
        "conversations.history": {
          "window_seconds": 60,
          "max_requests": 50,
          "retry_after_seconds": 30
        }
      }
    }
  }
}

​

Parameters

​

Seeding behavior

​

Resource fields

​

channels[]

​

channels[].messages[]

​

channels[].messages[].reactions[]

​

channels[].messages[].replies[]

​

direct_messages[]

​

direct_messages[].messages[]

​

users[]

​

canvases[]

​

tokens[]

​

API coverage and limitations

• Slack Web API methods for conversations, channels, messages, scheduled messages, users, reactions, pins, bookmarks, do-not-disturb, modal views, direct messages, and files.
• Block Kit messages on chat.postMessage: requests with a non-empty blocks array are accepted even when fallback text is blank or whitespace, and the submitted blocks are returned in the response and persisted in conversation history. Posts with both empty text and empty blocks still return no_text.
• Auth methods including api.test, auth.test, auth.revoke, and auth.teams.list.
• OAuth 2.0 authorization code grant through /oauth/v2/authorize and /api/oauth.v2.access, plus MCP OAuth aliases at /oauth/v2_user/authorize and /api/oauth.v2.user.access.
• Bot, user, and enterprise-style tokens, method-level OAuth scope enforcement, configurable token scopes, and missing-scope errors.
• File uploads, external upload completion, downloadable files, file-share events, workspace tier constraints, storage quotas, rate-limit simulation, event delivery, replay, and admin inspection.
• Slack CLI app management surface including manifest validate/create/update/export, app status, developer install/uninstall, app delete, connections open, hosted package upload placeholders, hosted environment variables (add/list/remove), and Slack CLI secondary API families covering activities, auth tickets and token rotation, app approvals, external auth, datastores, workflow triggers, function permissions, collaborators, icons, certified installs, and developer sandboxes. Point the Slack CLI at the twin by setting SLACK_API_URL to the twin’s /api/ base.
• Slack MCP Streamable HTTP endpoint at /mcp with JSON-RPC 2.0 initialize, tools/list, and tools/call, OAuth protected resource metadata at /.well-known/oauth-protected-resource/mcp, authorization server metadata at /.well-known/oauth-authorization-server, and Slack-shaped MCP tools (slack_search_messages, slack_search_messages_and_files, slack_search_public_and_private, slack_search_public, slack_search_files, slack_search_users, slack_search_channels, slack_list_channels, slack_read_channel, slack_send_message, slack_schedule_message, slack_send_message_draft, slack_read_thread, slack_list_users, slack_get_user, slack_read_user_profile, slack_create_canvas, slack_update_canvas, slack_read_canvas) that share state with the Web API surface.

• Channels start empty unless seeded or created through conversations.create.
• File upload limits and workspace features are controlled by the twin’s configured tier and constraints, not by a live Slack workspace.
• The REST, OAuth, Slack CLI, and Slack MCP surfaces are the fidelity targets; websocket/Socket Mode behavior is not described as primary support here.
• Hosted package upload endpoints (apps.hosted.generatePresignedPost, apps.hosted.upload) accept the CLI lifecycle but do not execute hosted runtimes.