# chat_start_stream

A execute tool on the Slack MCP server.

Agent View of the PolicyLayer registry record for `chat_start_stream`. HTML page: https://policylayer.com/tools/karbassi-slack-mcp/chat-start-stream

## Facts

- Tool: `chat_start_stream`
- Server: Slack (`karbassi/slack-mcp`) — https://policylayer.com/tools/karbassi-slack-mcp.md
- Homepage: https://github.com/karbassi/slack-mcp
- Risk category: Execute (High risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Rate-limited

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "chat_start_stream",
    "arguments": {}
  }
}
```

## Why chat_start_stream is rated High

The tool performs an action that triggers Slack's message streaming mechanism—an operation whose effects depend on arguments and cannot be undone without further action. This is Execute rather than Write because it initiates an active communication stream (a triggered operation) rather than simply creating/modifying a static piece of data.

From the tool's own definition: "Tool name is 'chat_start_stream' on a Slack MCP server that provides full access to Slack messaging and communication features."

## Use case

AI agents invoke chat_start_stream to trigger actions in Slack. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

## Recommended policy (PolicyLayer)

Verdict: **Rate-limited**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Slack:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "chat_start_stream": {
      "limits": [
        {
          "counter": "chat_start_stream_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}
```

## Other tools on Slack (232)

- `apps_manifest_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/apps-manifest-delete.md
- `apps_uninstall` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/apps-uninstall.md
- `auth_revoke` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/auth-revoke.md
- `bookmarks_remove` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/bookmarks-remove.md
- `cache_clear` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/cache-clear.md
- `calls_participants_remove` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/calls-participants-remove.md
- `canvases_access_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/canvases-access-delete.md
- `canvases_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/canvases-delete.md
- `channels_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/channels-delete.md
- `chat_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/chat-delete.md
- `chat_delete_scheduled_message` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/chat-delete-scheduled-message.md
- `conversations_kick` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/conversations-kick.md
- `drafts_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/drafts-delete.md
- `emoji_remove` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/emoji-remove.md
- `files_comments_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/files-comments-delete.md
- `files_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/files-delete.md
- `files_remote_remove` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/files-remote-remove.md
- `files_revoke_public_url` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/files-revoke-public-url.md
- `pins_remove` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/pins-remove.md
- `reactions_remove` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/reactions-remove.md
- `reminders_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/reminders-delete.md
- `saved_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/saved-delete.md
- `slack_lists_access_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/slack-lists-access-delete.md
- `slack_lists_items_delete` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/slack-lists-items-delete.md
- `slack_lists_items_delete_multiple` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/slack-lists-items-delete-multiple.md
- `stars_remove` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/stars-remove.md
- `team_external_teams_disconnect` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/team-external-teams-disconnect.md
- `users_admin_set_inactive` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/users-admin-set-inactive.md
- `users_delete_photo` — Destructive — https://policylayer.com/tools/karbassi-slack-mcp/users-delete-photo.md
- `apps_connections_open` — Execute — https://policylayer.com/tools/karbassi-slack-mcp/apps-connections-open.md
- …and 202 more: https://policylayer.com/tools/karbassi-slack-mcp.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

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Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=karbassi-slack-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/karbassi-slack-mcp