# chat_append_stream A write tool on the Slack MCP server. Agent View of the PolicyLayer registry record for `chat_append_stream`. HTML page: https://policylayer.com/tools/karbassi-slack-mcp/chat-append-stream ## Facts - Tool: `chat_append_stream` - Server: Slack (`karbassi/slack-mcp`) — https://policylayer.com/tools/karbassi-slack-mcp.md - Homepage: https://github.com/karbassi/slack-mcp - Risk category: Write (Medium 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_append_stream", "arguments": {} } } ``` ## Why chat_append_stream is rated Medium The tool appends to chat content, which is a write operation that modifies data reversibly. While the description is empty (lowering confidence slightly), the name and server context strongly suggest message modification. Severity is high because uncontrolled message appending could manipulate conversations, inject false information, or spam channels. From the tool's own definition: "Tool name 'chat_append_stream' indicates appending to chat messages; server description states it provides access to 'messages' among other Slack data; 'append' suggests modifying/adding content to existing messages or streams." ## Use case AI agents use chat_append_stream to create or update resources in Slack, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Slack environment. ## 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_append_stream": { "limits": [ { "counter": "chat_append_stream_rate", "window": "minute", "max": 30, "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` --- 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