Agent skill

slack

Slack API for sending messages, reading channels, and managing conversations. Use this skill to post messages, upload files, and interact with Slack workspaces.

View SKILL.md on GitHub Repository
Stars 163
Forks 31

Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/development/slack

SKILL.md

Slack API

Send messages, read channels, and interact with Slack workspaces.

When to Use

  • Send messages to channels or users
  • Read channel message history
  • Upload files to Slack
  • List channels and users
  • Add reactions to messages

Prerequisites

bash
export SLACK_BOT_TOKEN=xoxb-your-bot-token

Get Token

  1. Create app: https://api.slack.com/apps
  2. Add Bot Token Scopes (OAuth & Permissions):
  • chat:write - Send messages
  • channels:read - List public channels
  • channels:history - Read channel messages
  • files:write - Upload files
  • users:read - List users
  • reactions:write - Add reactions
  1. Install to Workspace
  2. Copy "Bot User OAuth Token" (xoxb-...)

Important: When using $VAR in a command that pipes to another command, wrap the command containing $VAR in bash -c '...'. Due to a Claude Code bug, environment variables are silently cleared when pipes are used directly.

bash
bash -c 'curl -s "https://api.example.com" -H "Authorization: Bearer $API_KEY"'

Core APIs

List Channels

bash
bash -c 'curl -s -H "Authorization: Bearer $SLACK_BOT_TOKEN" "https://slack.com/api/conversations.list?types=public_channel"' | jq '.channels[] | {id, name}'

Docs: https://docs.slack.dev/reference/methods/conversations.list

Get Channel History

Replace <channel-id> with the actual channel ID:

bash
bash -c 'curl -s -H "Authorization: Bearer $SLACK_BOT_TOKEN" "https://slack.com/api/conversations.history?channel=<channel-id>&limit=10"' | jq '.messages[] | {ts, user, text}'

Docs: https://docs.slack.dev/reference/methods/conversations.history

Send Message

Write to /tmp/request.json:

json
{
  "channel": "<channel-id>",
  "text": "Hello, World"
}
bash
bash -c 'curl -s -X POST "https://slack.com/api/chat.postMessage" -H "Authorization: Bearer $SLACK_BOT_TOKEN" -H "Content-Type: application/json" -d @/tmp/request.json'

Docs: https://docs.slack.dev/reference/methods/chat.postmessage

Send with Blocks

Write to /tmp/request.json:

json
{
  "channel": "<channel-id>",
  "text": "Notification",
  "blocks": [
    {
      "type": "section",
      "text": {"type": "mrkdwn", "text": "*Alert:* Something happened"}
    },
    {
      "type": "section",
      "fields": [
        {"type": "mrkdwn", "text": "*Status:*\nActive"},
        {"type": "mrkdwn", "text": "*Priority:*\nHigh"}
      ]
    }
  ]
}
bash
bash -c 'curl -s -X POST "https://slack.com/api/chat.postMessage" -H "Authorization: Bearer $SLACK_BOT_TOKEN" -H "Content-Type: application/json" -d @/tmp/request.json'

Block Kit Builder: https://app.slack.com/block-kit-builder

Reply in Thread

Write to /tmp/request.json:

json
{
  "channel": "<channel-id>",
  "thread_ts": "<thread-timestamp>",
  "text": "Thread reply"
}
bash
bash -c 'curl -s -X POST "https://slack.com/api/chat.postMessage" -H "Authorization: Bearer $SLACK_BOT_TOKEN" -H "Content-Type: application/json" -d @/tmp/request.json'

Update Message

Write to /tmp/request.json:

json
{
  "channel": "<channel-id>",
  "ts": "<message-timestamp>",
  "text": "Updated message"
}
bash
bash -c 'curl -s -X POST "https://slack.com/api/chat.update" -H "Authorization: Bearer $SLACK_BOT_TOKEN" -H "Content-Type: application/json" -d @/tmp/request.json'

Docs: https://docs.slack.dev/reference/methods/chat.update

Delete Message

Write to /tmp/request.json:

json
{
  "channel": "<channel-id>",
  "ts": "<message-timestamp>"
}
bash
bash -c 'curl -s -X POST "https://slack.com/api/chat.delete" -H "Authorization: Bearer $SLACK_BOT_TOKEN" -H "Content-Type: application/json" -d @/tmp/request.json'

List Users

bash
bash -c 'curl -s -H "Authorization: Bearer $SLACK_BOT_TOKEN" "https://slack.com/api/users.list"' | jq '.members[] | {id, name, real_name}'

Docs: https://docs.slack.dev/reference/methods/users.list

Get User by Email

Replace <user-email> with the actual email address:

bash
bash -c 'curl -s -H "Authorization: Bearer $SLACK_BOT_TOKEN" "https://slack.com/api/users.lookupByEmail?email=<user-email>"'

Docs: https://docs.slack.dev/reference/methods/users.lookupbyemail

Upload File

bash
curl -s -X POST 'https://slack.com/api/files.upload' -H "Authorization: Bearer $SLACK_BOT_TOKEN" -F 'channels=C1234567890' -F 'file=@/path/to/file.txt' -F 'title=My File'

Docs: https://docs.slack.dev/reference/methods/files.upload

Add Reaction

Write to /tmp/request.json:

json
{
  "channel": "<channel-id>",
  "timestamp": "<message-timestamp>",
  "name": "thumbsup"
}
bash
bash -c 'curl -s -X POST "https://slack.com/api/reactions.add" -H "Authorization: Bearer $SLACK_BOT_TOKEN" -H "Content-Type: application/json" -d @/tmp/request.json'

Docs: https://docs.slack.dev/reference/methods/reactions.add

Message Formatting

Syntax Result
*bold* bold
_italic_ italic
~strike~ strike
`code` code
<URL|text> hyperlink
<@U123> @mention user
<#C123> #channel link

Rate Limits

  • Tier 1: 1 request/second
  • Tier 2: 20 requests/minute
  • Tier 3: 50 requests/minute
  • Tier 4: 100 requests/minute

See: https://docs.slack.dev/apis/web-api/rate-limits

API Reference

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