Slack

The Slack skill lets Claude send messages to your Slack workspace. It supports two authentication modes: incoming webhooks (simple, single-channel) and bot tokens (multi-channel, thread replies, richer formatting).

Metadata

Field	Value
ID	slack
Category	notification
Required env vars	SLACK_WEBHOOK_URL or SLACK_BOT_TOKEN (at least one)

Tools

Tool	Description
slack_send_message	Send a message to a Slack channel via webhook or API
slack_send_thread_reply	Reply to an existing message thread (requires bot token)

Setup

You can configure Slack with either an incoming webhook or a bot token. Both work for sending messages; the bot token enables additional capabilities.

Option 1: Incoming webhook (simpler)

1. Go to api.slack.com/apps and create a new app (or use an existing one).
2. Enable Incoming Webhooks and add a webhook to the channel where you want notifications.
3. Set the environment variable:

export SLACK_WEBHOOK_URL="https://hooks.slack.com/services/T.../B.../..."

With a webhook, slack_send_message posts to the webhook’s configured channel. The channel parameter is ignored.

Option 2: Bot token (more capable)

1. Create a Slack app at api.slack.com/apps.
2. Under OAuth & Permissions, add the chat:write scope.
3. Install the app to your workspace and copy the bot token.
4. Invite the bot to the channels it needs to post in (/invite @your-bot).
5. Set the environment variable:

export SLACK_BOT_TOKEN="xoxb-..."

With a bot token, Claude can target any channel the bot has been invited to and reply to existing threads.

Both configured?

If both SLACK_WEBHOOK_URL and SLACK_BOT_TOKEN are set, the skill prefers the bot token API when a channel parameter is provided. It falls back to the webhook when no channel is specified. This lets you use the bot for targeted messages and the webhook as a default.

Bot token capabilities

Capability	Webhook	Bot token
Send to configured channel	Yes	Yes
Send to any channel	No	Yes
Thread replies	No	Yes
Block Kit formatting	Yes	Yes

Workflow usage

Triage workflow:

• notify — Send a summary of the triage result including severity, root cause, and a link to the created issue.

Implement workflow:

• notify — Send a message with the issue reference, PR link, and a brief summary of the changes.

The Slack skill is interchangeable with the Notification skill at notification nodes. Configure whichever channels your team uses.